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Author Scalise, E.; Houssa, M.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Inelastic electron tunneling spectroscopy of HfO2 gate stacks : a study based on first-principles modeling Type A1 Journal article
Year 2011 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 99 Issue 13 Pages 132101,1-132101,3
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract A first-principles modeling approach is used to investigate the vibrational properties of HfO2. The calculated phonon density of states is compared to experimental results obtained from inelastic electron tunneling spectroscopy (IETS) of various metal-oxide-semiconductor devices with HfO2 gate stacks. This comparison provides deep insights into the nature of the signatures of the complicated IETS spectra and provides valuable structural information about the gate stack, such as the possible presence of oxygen vacancies in jet-vapour deposited HfO2. Important structural differences between the interface of atomic-layer or molecular-beam deposited HfO2 and the Si substrate are also revealed.
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000295618000036 Publication Date 2011-09-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 1 Open Access
Notes Approved Most recent IF: 3.411; 2011 IF: 3.844
Call Number UA @ lucian @ c:irua:93611 Serial 1606
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Author Chen, Y.Y.; Pourtois, G.; Adelmann, C.; Goux, L.; Govoreanu, B.; Degreave, R.; Jurczak, M.; Kittl, J.A.; Groeseneken, G.; Wouters, D.J.
Title Insights into Ni-filament formation in unipolar-switching Ni/HfO2/TiN resistive random access memory device Type A1 Journal article
Year 2012 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 100 Issue 11 Pages 113513-113513,4
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In this letter, CMOS-compatible Ni/HfO2/TiN resistive random access memory stacks demonstrated attractive unipolar switching properties, showing >10(3) endurance and long retention at 150 degrees C. The Ni bottom electrode (BE) improved the switching yield over the NiSiPt BE. To better understand the unipolar forming mechanism, ab initio simulation and time of flight-secondary ion mass spectroscopy were utilized. Compared to the NiSiPt BE, Ni BE gives larger Ni diffusion in the HfO2 and lower formation enthalpy of Ni2+ species during electrical forming. Both the electrical and physical results supported a Ni-injection mechanism for the filament formation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3695078]
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000302204900091 Publication Date 2012-03-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 29 Open Access
Notes Approved Most recent IF: 3.411; 2012 IF: 3.794
Call Number UA @ lucian @ c:irua:98295 Serial 1674
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Author Hardy, A.; Van Elshocht, S.; De Dobbelaere, C.; Hadermann, J.; Pourtois, G.; De Gendt, S.; Afanas'ev, V.V.; Van Bael, M.K.
Title Properties and thermal stability of solution processed ultrathin, high-k bismuth titanate (Bi2Ti2O7) films Type A1 Journal article
Year 2012 Publication Materials research bulletin Abbreviated Journal Mater Res Bull
Volume 47 Issue 3 Pages 511-517
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Ultrathin bismuth titanate films (Bi2Ti2O7, 5-25 nm) are deposited onto SiO2/Si substrates by aqueous chemical solution deposition and their evolution during annealing is studied. The films crystallize into a preferentially oriented, pure pyrochlore phase between 500 and 700 degrees C, depending on the film thickness and the total thermal budget. Crystallization causes a strong increase of surface roughness compared to amorphous films. An increase of the interfacial layer thickness is observed after anneal at 600 degrees C, together with intermixing of bismuth with the substrate as shown by TEM-EDX. The band gap was determined to be similar to 3 eV from photoconductivity measurements and high dielectric constants between 30 and 130 were determined from capacitance voltage measurements, depending on the processing conditions. (C) 2012 Elsevier Ltd. All rights reserved.
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Corporate Author Thesis
Publisher Place of Publication (down) New York, N.Y. Editor
Language Wos 000301994100001 Publication Date 2012-01-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0025-5408; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.446 Times cited Open Access
Notes Approved Most recent IF: 2.446; 2012 IF: 1.913
Call Number UA @ lucian @ c:irua:97797 Serial 2727
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Author Delabie, A.; Sioncke, S.; Rip, J.; Van Elshocht, S.; Pourtois, G.; Mueller, M.; Beckhoff, B.; Pierloot, K.
Title Reaction mechanisms for atomic layer deposition of aluminum oxide on semiconductor substrates Type A1 Journal article
Year 2012 Publication Journal of vacuum science and technology: A: vacuum surfaces and films Abbreviated Journal J Vac Sci Technol A
Volume 30 Issue 1 Pages 01a127-01a127,10
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In this work, we have studied the TMA/H(2)O (TMA Al(CH(3))(3)) atomic layer deposition (ALD) of Al(2)O(3) on hydroxyl (OH) and thiol (SH) terminated semiconductor substrates. Total reflection x-ray fluorescence reveals a complex growth-per-cycle evolution during the early ALD reaction cycles. OH and SH terminated surfaces demonstrate growth inhibition from the second reaction cycle on. Theoretical calculations, based on density functional theory, are performed on cluster models to investigate the first TMA/H(2)O reaction cycle. Based on the theoretical results, we discuss possible mechanisms for the growth inhibition from the second reaction cycle on. In addition, our calculations show that AlCH(3) groups are hydrolyzed by a H(2)O molecule adsorbed on a neighboring Al atom, independent of the type of backbonds (Si-O, Ge-O, or Ge-S) of AlCH(3). The coordination of Al remains four-fold after the first TMA/H(2)O reaction cycle. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3664090]
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Corporate Author Thesis
Publisher Place of Publication (down) New York, N.Y. Editor
Language Wos 000298992800027 Publication Date 2011-12-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0734-2101; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.374 Times cited 41 Open Access
Notes Approved Most recent IF: 1.374; 2012 IF: 1.432
Call Number UA @ lucian @ c:irua:96253 Serial 2818
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Author Scalise, E.; Houssa, M.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Structural and vibrational properties of amorphous GeO2 from first-principles Type A1 Journal article
Year 2011 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 98 Issue 20 Pages 202110,1-202110,3
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The structural and vibrational properties of amorphous germanium oxide (a-GeO<sub>2</sub>) are investigated using first-principles calculations based on density functional theory. We first generate an a-GeO<sub>2</sub> structure by first-principles molecular dynamics and analyze its structural properties. The vibrational spectra is then calculated within a density-functional approach. Both static and dynamic properties are in good agreement with experimental data. We next generate defects in our structure (oxygen vacancies with several density and charge states) and consider the most stable atomic configurations, focusing on the vibrational features of threefold coordinated O and divalent Ge centers.
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000290812100038 Publication Date 2011-05-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 226 Open Access
Notes Approved Most recent IF: 3.411; 2011 IF: 3.844
Call Number UA @ lucian @ c:irua:90222 Serial 3202
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Author Clima, S.; Chen, Y.Y.; Chen, C.Y.; Goux, L.; Govoreanu, B.; Degraeve, R.; Fantini, A.; Jurczak, M.; Pourtois, G.
Title First-principles thermodynamics and defect kinetics guidelines for engineering a tailored RRAM device Type A1 Journal article
Year 2016 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 119 Issue 119 Pages 225107
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Resistive Random Access Memories are among the most promising candidates for the next generation of non-volatile memory. Transition metal oxides such as HfOx and TaOx attracted a lot of attention due to their CMOS compatibility. Furthermore, these materials do not require the inclusion of extrinsic conducting defects since their operation is based on intrinsic ones (oxygen vacancies). Using Density Functional Theory, we evaluated the thermodynamics of the defects formation and the kinetics of diffusion of the conducting species active in transition metal oxide RRAM materials. The gained insights based on the thermodynamics in the Top Electrode, Insulating Matrix and Bottom Electrode and at the interfaces are used to design a proper defect reservoir, which is needed for a low-energy reliable switching device. The defect reservoir has also a direct impact on the retention of the Low Resistance State due to the resulting thermodynamic driving forces. The kinetics of the diffusing conducting defects in the Insulating Matrix determine the switching dynamics and resistance retention. The interface at the Bottom Electrode has a significant impact on the low-current operation and long endurance of the memory cell. Our first-principles findings are confirmed by experimental measurements on fabricated RRAM devices. Published by AIP Publishing.
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Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000378925400035 Publication Date 2016-06-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; 1089-7550 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 17 Open Access
Notes Approved Most recent IF: 2.068
Call Number UA @ lucian @ c:irua:134651 Serial 4181
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Author Dhayalan, S.K.; Kujala, J.; Slotte, J.; Pourtois, G.; Simoen, E.; Rosseel, E.; Hikavyy, A.; Shimura, Y.; Iacovo, S.; Stesmans, A.; Loo, R.; Vandervorst, W.;
Title On the manifestation of phosphorus-vacancy complexes in epitaxial Si:P films Type A1 Journal article
Year 2016 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 108 Issue 108 Pages 082106
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In situ doped epitaxial Si: P films with P concentrations > 1 x 10(21) at./cm(3) are suitable for source-drain stressors of n-FinFETs. These films combine the advantages of high conductivity derived from the high P doping with the creation of tensile strain in the Si channel. It has been suggested that the tensile strain developed in the Si: P films is due to the presence of local Si3P4 clusters, which however do not contribute to the electrical conductivity. During laser annealing, the Si3P4 clusters are expected to disperse resulting in an increased conductivity while the strain reduces slightly. However, the existence of Si3P4 is not proven. Based on first-principles simulations, we demonstrate that the formation of vacancy centered Si3P4 clusters, in the form of four P atoms bonded to a Si vacancy, is thermodynamically favorable at such high P concentrations. We suggest that during post epi-growth annealing, a fraction of the P atoms from these clusters are activated, while the remaining part goes into interstitial sites, thereby reducing strain. We corroborate our conjecture experimentally using positron annihilation spectroscopy, electron spin resonance, and Rutherford backscattering ion channeling studies. (C) 2016 AIP Publishing LLC.
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000373057000023 Publication Date 2016-02-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; 1077-3118 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 9 Open Access
Notes Approved Most recent IF: 3.411
Call Number UA @ lucian @ c:irua:133245 Serial 4217
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Author Lu, A.K.A.; Pourtois, G.; Agarwal, T.; Afzalian, A.; Radu, I.P.; Houssa, M.
Title Origin of the performances degradation of two-dimensional-based metal-oxide-semiconductor field effect transistors in the sub-10 nm regime: A first-principles study Type A1 Journal article
Year 2016 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 108 Issue 4 Pages 043504
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The impact of the scaling of the channel length on the performances of metal-oxide-semiconductor field effect transistors, based on two-dimensional (2D) channel materials, is theoretically investigated, using density functional theory combined with the non-equilibrium Green's function method. It is found that the scaling of the channel length below 10nm leads to strong device performance degradations. Our simulations reveal that this degradation is essentially due to the tunneling current flowing between the source and the drain in these aggressively scaled devices. It is shown that this electron tunneling process is modulated by the effective mass of the 2D channel material, and sets the limit of the scaling in future transistor designs. (C) 2016 AIP Publishing LLC.
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000375217200061 Publication Date 2016-01-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; 1077-3118 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 4 Open Access
Notes Approved Most recent IF: 3.411
Call Number UA @ lucian @ c:irua:144750 Serial 4677
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Author Dutta, S.; Sankaran, K.; Moors, K.; Pourtois, G.; Van Elshocht, S.; Bommels, J.; Vandervorst, W.; Tokei, Z.; Adelmann, C.
Title Thickness dependence of the resistivity of platinum-group metal thin films Type A1 Journal article
Year 2017 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 122 Issue 2 Pages 025107
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We report on the thin film resistivity of several platinum-group metals (Ru, Pd, Ir, and Pt). Platinum-group thin films show comparable or lower resistivities than Cu for film thicknesses below about 5 nm due to a weaker thickness dependence of the resistivity. Based on experimentally determined mean linear distances between grain boundaries as well as ab initio calculations of the electron mean free path, the data for Ru, Ir, and Cu were modeled within the semiclassical Mayadas-Shatzkes model [Phys. Rev. B 1, 1382 (1970)] to assess the combined contributions of surface and grain boundary scattering to the resistivity. For Ru, the modeling results indicated that surface scattering was strongly dependent on the surrounding material with nearly specular scattering at interfaces with SiO2 or air but with diffuse scattering at interfaces with TaN. The dependence of the thin film resistivity on the mean free path is also discussed within the Mayadas-Shatzkes model in consideration of the experimental findings. Published by AIP Publishing.
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Corporate Author Thesis
Publisher American Institute of Physics Place of Publication (down) New York, N.Y. Editor
Language Wos 000405663800038 Publication Date 2017-07-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; 1089-7550 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 42 Open Access Not_Open_Access
Notes Approved Most recent IF: 2.068
Call Number UA @ lucian @ c:irua:145213 Serial 4729
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Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Method to quantify the delocalization of electronic states in amorphous semiconductors and its application to assessing charge carrier mobility of p-type amorphous oxide semiconductors Type A1 Journal article
Year 2018 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 97 Issue 4 Pages 045208
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Amorphous semiconductors are usually characterized by a low charge carrier mobility, essentially related to their lack of long-range order. The development of such material with higher charge carrier mobility is hence challenging. Part of the issue comes from the difficulty encountered by first-principles simulations to evaluate concepts such as the electron effective mass for disordered systems since the absence of periodicity induced by the disorder precludes the use of common concepts derived from condensed matter physics. In this paper, we propose a methodology based on first-principles simulations that partially solves this problem, by quantifying the degree of delocalization of a wave function and of the connectivity between the atomic sites within this electronic state. We validate the robustness of the proposed formalism on crystalline and molecular systems and extend the insights gained to disordered/amorphous InGaZnO4 and Si. We also explore the properties of p-type oxide semiconductor candidates recently reported to have a low effective mass in their crystalline phases [G. Hautier et al., Nat. Commun. 4, 2292 (2013)]. Although in their amorphous phase none of the candidates present a valence band with delocalization properties matching those found in the conduction band of amorphous InGaZnO4, three of the seven analyzed materials show some potential. The most promising candidate, K2Sn2O3, is expected to possess in its amorphous phase a slightly higher hole mobility than the electron mobility in amorphous silicon.
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Corporate Author Thesis
Publisher American Physical Society Place of Publication (down) New York, N.Y Editor
Language Wos 000423427600005 Publication Date 2018-01-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 2 Open Access OpenAccess
Notes Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:149318 Serial 4943
Permanent link to this record
 
 
Author Adelmann, C.; Wen, L.G.; Peter, A.P.; Pourtois, G.; et al.
Title Alternative metals for advanced interconnects Type P1 Proceeding
Year 2014 Publication 2014 Ieee International Interconnect Technology Conference / Advanced Metallization Conference (iitc/amc) Abbreviated Journal
Volume Issue Pages 173-175
Keywords P1 Proceeding; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We discuss the selection criteria for alternative metals in order to fulfill the requirements necessary for interconnects at half pitch values below 10 nm. The performance of scaled interconnects using transition metal germanides and CoAl alloys as metallization are studied and compared to conventional Cu and W interconnects.
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Corporate Author Thesis
Publisher Ieee Place of Publication (down) New york Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 978-1-4799-5018-8 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:127033 Serial 91
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Author Sankaran, K.; Clima, S.; Mees, M.; Adelmann, C.; Tokei, Z.; Pourtois, G.
Title Exploring alternative metals to Cu and W for interconnects : an ab initio Insight Type P1 Proceeding
Year 2014 Publication 2014 Ieee International Interconnect Technology Conference / Advanced Metallization Conference (iitc/amc) Abbreviated Journal
Volume Issue Pages 193-195
Keywords P1 Proceeding; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The properties of alternative metals to Cu and W for interconnect applications are reviewed based on first-principles simulations and benchmarked in terms of intrinsic bulk resistivity and electromigration.
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Corporate Author Thesis
Publisher Ieee Place of Publication (down) New york Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 978-1-4799-5018-8 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:127034 Serial 1149
Permanent link to this record
 
 
Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Effects of hole self-trapping by polarons on transport and negative bias illumination stress in amorphous-IGZO Type A1 Journal article
Year 2018 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 123 Issue 16 Pages 161513
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The effects of hole injection in amorphous indium-gallium-zinc-oxide (a-IGZO) are analyzed by means of first-principles calculations. The injection of holes in the valence band tail states leads to their capture as a polaron, with high self-trapping energies (from 0.44 to 1.15 eV). Once formed, they mediate the formation of peroxides and remain localized close to the hole injection source due to the presence of a large diffusion energy barrier (of at least 0.6 eV). Their diffusion mechanism can be mediated by the presence of hydrogen. The capture of these holes is correlated with the low off-current observed for a-IGZO transistors, as well as with the difficulty to obtain a p-type conductivity. The results further support the formation of peroxides as being the root cause of Negative Bias Illumination Stress (NBIS). The strong self-trapping substantially reduces the injection of holes from the contact and limits the creation of peroxides from a direct hole injection. In the presence of light, the concentration of holes substantially rises and mediates the creation of peroxides, responsible for NBIS. Published by AIP Publishing.
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Corporate Author Thesis
Publisher Amer inst physics Place of Publication (down) Melville Editor
Language Wos 000431147200043 Publication Date 2017-10-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; 1089-7550 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 4 Open Access OpenAccess
Notes Approved Most recent IF: 2.068
Call Number UA @ lucian @ c:irua:151570 Serial 5021
Permanent link to this record
 
 
Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor : structure, tail states and strain effects Type A1 Journal article
Year 2015 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 48 Issue 48 Pages 435104
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen-metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced variation in the effective mass is found to be negligible (less than 1%).
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Corporate Author Thesis
Publisher Place of Publication (down) London Editor
Language Wos 000365876300012 Publication Date 2015-09-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.588 Times cited 23 Open Access
Notes Approved Most recent IF: 2.588; 2015 IF: 2.721
Call Number UA @ lucian @ c:irua:130277 Serial 4153
Permanent link to this record
 
 
Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Origin of the apparent delocalization of the conduction band in a high-mobility amorphous semiconductor Type A1 Journal article
Year 2017 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 29 Issue 25 Pages 255702
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In this paper, we show that the apparent delocalization of the conduction band reported from first-principles simulations for the high-mobility amorphous oxide semiconductor InGaZnO4 (a-IGZO) is an artifact induced by the periodic conditions imposed to the model. Given a sufficiently large unit-cell dimension (over 40 angstrom), the conduction band becomes localized. Such a model size is up to four times the size of commonly used models for the study of a-IGZO. This finding challenges the analyses done so far on the nature of the defects and on the interpretation of numerous electrical measurements. In particular, we re-interpret the meaning of the computed effective mass reported so far in literature. Our finding also applies to materials such as SiZnSnO, ZnSnO, InZnSnO, In2O3 or InAlZnO4 whose models have been reported to display a fully delocalized conduction band in the amorphous phase.
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Corporate Author Thesis
Publisher Place of Publication (down) London Editor
Language Wos 000402434900002 Publication Date 2017-02-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.649 Times cited 5 Open Access Not_Open_Access
Notes Approved Most recent IF: 2.649
Call Number UA @ lucian @ c:irua:144183 Serial 4676
Permanent link to this record
 
 
Author Compemolle, S.; Pourtois, G.; Sorée, B.; Magnus, W.; Chibotaru, L.F.; Ceulemans, A.
Title Conductance of a copper-nanotube bundle interface: impact of interface geometry and wave-function interference Type A1 Journal article
Year 2008 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 77 Issue 19 Pages 193406,1-4
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract
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Corporate Author Thesis
Publisher Place of Publication (down) Lancaster, Pa Editor
Language Wos 000256971600032 Publication Date 2008-05-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 8 Open Access
Notes Approved Most recent IF: 3.836; 2008 IF: 3.322
Call Number UA @ lucian @ c:irua:70215 Serial 479
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Author Mehta, A.N.; Zhang, H.; Dabral, A.; Richard, O.; Favia, P.; Bender, H.; Delabie, A.; Caymax, M.; Houssa, M.; Pourtois, G.; Vandervorst, W.
Title Structural characterization of SnS crystals formed by chemical vapour deposition Type A1 Journal article
Year 2017 Publication Journal of microscopy T2 – 20th International Conference on Microscopy of Semiconducting Materials, (MSM), APR 09-13, 2017, Univ Oxford, Univ Oxford, Oxford, ENGLAND Abbreviated Journal J Microsc-Oxford
Volume 268 Issue 3 Pages 276-287
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract <script type='text/javascript'>document.write(unpmarked('The crystal and defect structure of SnS crystals grown using chemical vapour deposition for application in electronic devices are investigated. The structural analysis shows the presence of two distinct crystal morphologies, that is thin flakes with lateral sizes up to 50 m and nanometer scale thickness, and much thicker but smaller crystallites. Both show similar Raman response associated with SnS. The structural analysis with transmission electron microscopy shows that the flakes are single crystals of -SnS with [010] normal to the substrate. Parallel with the surface of the flakes, lamellae with varying thickness of a new SnS phase are observed. High-resolution transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), first-principles simulations (DFT) and nanobeam diffraction (NBD) techniques are employed to characterise this phase in detail. DFT results suggest that the phase is a strain stabilised \u0027 one grown epitaxially on the -SnS crystals. TEM analysis shows that the crystallites are also -SnS with generally the [010] direction orthogonal to the substrate. Contrary to the flakes the crystallites consist of two to four grains which are tilted up to 15 degrees relative to the substrate. The various grain boundary structures and twin relations are discussed. Under high-dose electron irradiation, the SnS structure is reduced and -Sn formed. It is shown that this damage only occurs for SnS in direct contact with SiO2. Lay description SnS is a p-type semiconductor, which has attracted significant interest for electronic devices due to its unique properties, low-toxicity and abundance of Sn in nature. Although in the past it has been most extensively studied as the absorber material in solar cells, it has recently garnered interest for application as a p-type two-dimensional semiconductor in nanoelectronic devices due to its anisotropic layered structure similar to the better known phosphorene. Tin sulphide can take the form of several phases and the electronic properties of the material depend strongly on its crystal structure. It is therefore crucial to study the crystal structure of the material in order to predict the electronic properties and gain insight into the growth mechanism. In this work, SnS crystals deposited using a chemical vapour deposition technique are investigated extensively for their crystal and defect structure using transmission electron microscopy (TEM) and related techniques. We find the presence of two distinct crystal morphologies, that is thin flakes with lateral sizes up to 50 m and nm scale thickness, and much thicker but smaller crystallites. The flakes are single crystals of -SnS and contain lamellae with varying thickness of a different phase which appear to be -SnS at first glance. High-resolution scanning transmission electron microscopy is used to characterise these lamellae where the annular bright field (ABF) mode better reveals the position of the sulphur columns. The sulphur columns in the lamellae are found to be shifted relative to the -SnS structure which indicates the formation of a new phase which is a distorted version of the phase which we tentatively refer to as \u0027-SnS. Simulations based on density functional theory (DFT) are used to model the interface and a similar shift of sulphur columns in the -SnS layer is observed which takes place as a result of strong interaction at the interface between the two phases resulting in strain transfer. Nanobeam electron diffraction (NBD) is used to map the lattice mismatch in the thickness of the flakes which reveals good in-plane matching and some expansion out-of-plane in the lamellae. Contrary to the flakes the crystallites are made solely of -SnS and consist of two to four grains which are tilted up to 15 degrees relative to the substrate. The various grain boundary structures and twin relations are discussed. At high electron doses, SnS is reduced to -Sn, however the damage occurs only for SnS in direct contact with SiO2.'));
Address
Corporate Author Thesis
Publisher Wiley Place of Publication (down) Hoboken Editor
Language Wos 000415900300009 Publication Date 2017-09-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2720 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.692 Times cited 2 Open Access Not_Open_Access
Notes Approved Most recent IF: 1.692
Call Number UA @ lucian @ c:irua:147692 Serial 4898
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Author Lu, A.K.A.; Houssa, M.; Luisier, M.; Pourtois, G.
Title Impact of layer alignment on the behavior of MoS2-ZrS2 tunnel field-effect transistors : an ab initio study Type A1 Journal article
Year 2017 Publication Physical review applied Abbreviated Journal Phys Rev Appl
Volume 8 Issue 3 Pages 034017
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Tunnel field-effect transistors based on van der Waals heterostructures are emerging device concepts for low-power applications, auguring sub-60 mV/dec subthreshold swing values. In these devices, the channel is built from a stack of several different two-dimensional materials whose nature allows tailoring the band alignments and enables a good electrostatic control of the device. In this work, we propose a theoretical study of the variability of the performances of a MoS2-ZrS2 tunnel field-effect transistor induced by fluctuations of the relative position or the orientation of the layers. Our results indicate that although a steep subthreshold slope (20 mV/dec) is achievable, fluctuations in the relative orientation of the ZrS2 layer with respect to the MoS2 one lead to a significant variability in the tunneling current by about one decade. This arises from changes in the orbital overlap between the layers and from the modulation of the transport direction.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication (down) College Park, Md Editor
Language Wos 000411460400001 Publication Date 2017-09-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2331-7019 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.808 Times cited 6 Open Access OpenAccess
Notes Approved Most recent IF: 4.808
Call Number UA @ lucian @ c:irua:146741 Serial 4785
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Author De Clercq, M.; Moors, K.; Sankaran, K.; Pourtois, G.; Dutta, S.; Adelmann, C.; Magnus, W.; Sorée, B.
Title Resistivity scaling model for metals with conduction band anisotropy Type A1 Journal article
Year 2018 Publication Physical review materials Abbreviated Journal
Volume 2 Issue 3 Pages 033801
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract It is generally understood that the resistivity of metal thin films scales with film thickness mainly due to grain boundary and boundary surface scattering. Recently, several experiments and ab initio simulations have demonstrated the impact of crystal orientation on resistivity scaling. The crystal orientation cannot be captured by the commonly used resistivity scaling models and a qualitative understanding of its impact is currently lacking. In this work, we derive a resistivity scaling model that captures grain boundary and boundary surface scattering as well as the anisotropy of the band structure. The model is applied to Cu and Ru thin films, whose conduction bands are (quasi-) isotropic and anisotropic, respectively. After calibrating the anisotropy with ab initio simulations, the resistivity scaling models are compared to experimental resistivity data and a renormalization of the fitted grain boundary reflection coefficient can be identified for textured Ru.
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Corporate Author Thesis
Publisher American Physical Society Place of Publication (down) College Park, Md Editor
Language Wos 000426787600001 Publication Date 2018-03-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2475-9953 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes ; The authors acknowledge the support by the Fonds National de la Recherche Luxembourg (ATTRACT Grant No. 7556175). ; Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:149866UA @ admin @ c:irua:149866 Serial 4947
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Author de de Meux, A.J.; Pourtois, G.; Genoe, J.; Heremans, P.
Title Defects in amorphous semiconductors : the case of amorphous indium gallium zinc oxide Type A1 Journal article
Year 2018 Publication Physical review applied Abbreviated Journal Phys Rev Appl
Volume 9 Issue 9 Pages 054039
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Based on a rational classification of defects in amorphous materials, we propose a simplified model to describe intrinsic defects and hydrogen impurities in amorphous indium gallium zinc oxide (a-IGZO). The proposed approach consists of organizing defects into two categories: point defects, generating structural anomalies such as metal-metal or oxygen-oxygen bonds, and defects emerging from changes in the material stoichiometry, such as vacancies and interstitial atoms. Based on first-principles simulations, it is argued that the defects originating from the second group always act as perfect donors or perfect acceptors. This classification simplifies and rationalizes the nature of defects in amorphous phases. In a-IGZO, the most important point defects are metal-metal bonds (or small metal clusters) and peroxides (O-O single bonds). Electrons are captured by metal-metal bonds and released by the formation of peroxides. The presence of hydrogen can lead to two additional types of defects: metal-hydrogen defects, acting as acceptors, and oxygen-hydrogen defects, acting as donors. The impact of these defects is linked to different instabilities observed in a-IGZO. Specifically, the diffusion of hydrogen and oxygen is connected to positive-and negative-bias stresses, while negative-bias illumination stress originates from the formation of peroxides.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication (down) College Park, Md Editor
Language Wos 000433070900003 Publication Date 2018-05-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2331-7019 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.808 Times cited 7 Open Access OpenAccess
Notes Approved Most recent IF: 4.808
Call Number UA @ lucian @ c:irua:151497 Serial 5019
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Author Houssa, M.; van den Broek, B.; Scalise, E.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title An electric field tunable energy band gap at silicene/(0001) ZnS interfaces Type A1 Journal article
Year 2013 Publication Physical chemistry, chemical physics Abbreviated Journal Phys Chem Chem Phys
Volume 15 Issue 11 Pages 3702-3705
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The interaction of silicene, the silicon counterpart of graphene, with (0001) ZnS surfaces is investigated theoretically, using first-principles simulations. The charge transfer occurring at the silicene/(0001) ZnS interface leads to the opening of an indirect energy band gap of about 0.7 eV in silicene. Remarkably, the nature (indirect or direct) and magnitude of the energy band gap of silicene can be controlled by an external electric field: the energy gap is predicted to become direct for electric fields larger than about 0.5 V angstrom(-1), and the direct energy gap decreases approximately linearly with the applied electric field. The predicted electric field tunable energy band gap of the silicene/(0001) ZnS interface is very promising for its potential use in nanoelectronic devices.
Address
Corporate Author Thesis
Publisher Place of Publication (down) Cambridge Editor
Language Wos 000315165100002 Publication Date 2013-01-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1463-9076;1463-9084; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.123 Times cited 74 Open Access
Notes Approved Most recent IF: 4.123; 2013 IF: 4.198
Call Number UA @ lucian @ c:irua:107702 Serial 94
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Author Khalilov, U.; Pourtois, G.; Bogaerts, A.; van Duin, A.C.T.; Neyts, E.C.
Title Reactive molecular dynamics simulations on SiO2-coated ultra-small Si-nanowires Type A1 Journal article
Year 2013 Publication Nanoscale Abbreviated Journal Nanoscale
Volume 5 Issue 2 Pages 719-725
Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The application of coreshell SiSiO2 nanowires as nanoelectronic devices strongly depends on their structure, which is difficult to tune precisely. In this work, we investigate the formation of the coreshell nanowires at the atomic scale, by reactive molecular dynamics simulations. The occurrence of two temperature-dependent oxidation mechanisms of ultra-small diameter Si-NWs is demonstrated. We found that control over the Si-core radius and the SiOx (x ≤ 2) oxide shell is possible by tuning the growth temperature and the initial Si-NW diameter. Two different structures were obtained, i.e., ultrathin SiO2 silica nanowires at high temperature and Si core|ultrathin SiO2 silica nanowires at low temperature. The transition temperature is found to linearly decrease with the nanowire curvature. Finally, the interfacial stress is found to be responsible for self-limiting oxidation, depending on both the initial Si-NW radius and the oxide growth temperature. These novel insights allow us to gain control over the exact morphology and structure of the wires, as is needed for their application in nanoelectronics.
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Corporate Author Thesis
Publisher Place of Publication (down) Cambridge Editor
Language Wos 000313426200036 Publication Date 2012-11-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2040-3364;2040-3372; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 7.367 Times cited 17 Open Access
Notes Approved Most recent IF: 7.367; 2013 IF: 6.739
Call Number UA @ lucian @ c:irua:102584 Serial 2824
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Author Schoeters, B.; Neyts, E.C.; Khalilov, U.; Pourtois, G.; Partoens, B.
Title Stability of Si epoxide defects in Si nanowires : a mixed reactive force field/DFT study Type A1 Journal article
Year 2013 Publication Physical chemistry, chemical physics Abbreviated Journal Phys Chem Chem Phys
Volume 15 Issue 36 Pages 15091-15097
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Modeling the oxidation process of silicon nanowires through reactive force field based molecular dynamics simulations suggests that the formation of Si epoxide defects occurs both at the Si/SiOx interface and at the nanowire surface, whereas for flat surfaces, this defect is experimentally observed to occur only at the interface as a result of stress. In this paper, we argue that the increasing curvature stabilizes the defect at the nanowire surface, as suggested by our density functional theory calculations. The latter can have important consequences for the opto-electronic properties of thin silicon nanowires, since the epoxide induces an electronic state within the band gap. Removing the epoxide defect by hydrogenation is expected to be possible but becomes increasingly difficult with a reduction of the diameter of the nanowires.
Address
Corporate Author Thesis
Publisher Place of Publication (down) Cambridge Editor
Language Wos 000323520600029 Publication Date 2013-07-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1463-9076;1463-9084; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.123 Times cited 3 Open Access
Notes ; BS gratefully acknowledges financial support of the IWT, Institute for the Promotion of Innovation by Science and Technology in Flanders, via the SBO project “SilaSol”. This work was carried out using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen, a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish government and the Universiteit Antwerpen. ; Approved Most recent IF: 4.123; 2013 IF: 4.198
Call Number UA @ lucian @ c:irua:110793 Serial 3130
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Author Mees, M.J.; Pourtois, G.; Rosciano, F.; Put, B.; Vereecken, P.M.; Stesmans, A.
Title First-principles material modeling of solid-state electrolytes with the spinel structure Type A1 Journal article
Year 2014 Publication Physical chemistry, chemical physics Abbreviated Journal Phys Chem Chem Phys
Volume Issue Pages
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Ionic diffusion through the novel (AlxMg1-2xLix)Al2O4 spinel electrolyte is investigated using first-principles calculations, combined with the Kinetic Monte Carlo algorithm. We observe that the ionic diffusion increases with the lithium content x. Furthermore, the structural parameters, formation enthalpies and electronic structures of (AlxMg1-2xLix)Al2O4 are calculated for various stoichiometries. The overall results indicate the (AlxMg1-2xLix)Al2O4 stoichiometries x = 0.2...0.3 as most promising. The (AlxMg1-2xLix)Al2O4 electrolyte is a potential candidate for the all-spinel solid-state battery stack, with the material epitaxially grown between well-known spinel electrodes, such as LiyMn2O4 and Li4+3yTi5O12 (y = 0...1). Due to their identical crystal structure, a good electrolyte-electrode interface is expected.
Address
Corporate Author Thesis
Publisher Place of Publication (down) Cambridge Editor
Language Wos 000332395700048 Publication Date 2014-02-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1463-9076; 1463-9084 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.123 Times cited 8 Open Access
Notes Approved Most recent IF: 4.123; 2014 IF: 4.493
Call Number UA @ lucian @ c:irua:128893 Serial 4520
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Author Scalise, E.; Houssa, M.; Cinquanta, E.; Grazianetti, C.; van den Broek, B.; Pourtois, G.; Stesmans, A.; Fanciulli, M.; Molle, A.
Title Engineering the electronic properties of silicene by tuning the composition of MoX2 and GaX (X = S,Se,Te) chalchogenide templates Type A1 Journal article
Year 2014 Publication 2D materials Abbreviated Journal 2D Mater
Volume 1 Issue 1 Pages 011010
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract By using first-principles simulations, we investigate the interaction of a 2D silicon layer with two classes of chalcogenide-layered compounds, namely MoX2 and GaX (X = S, Se, Te). A rather weak (van der Waals) interaction between the silicene layers and the chalcogenide layers is predicted. We found that the buckling of the silicene layer is correlated to the lattice mismatch between the silicene layer and the MoX2 or GaX template. The electronic properties of silicene on these different templates largely depend on the buckling of the silicene layer: highly buckled silicene on MoS2 is predicted to be metallic, while low buckled silicene on GaS and GaSe is predicted to be semi-metallic, with preserved Dirac cones at the K points. These results indicate new routes for artificially engineering silicene nanosheets, providing tailored electronic properties of this 2D layer on non-metallic substrates. These non-metallic templates also open the way to the possible integration of silicene in future nanoelectronic devices.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication (down) Bristol Editor
Language Wos 000353649900011 Publication Date 2014-05-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 49 Open Access
Notes Approved Most recent IF: 6.937; 2014 IF: NA
Call Number UA @ lucian @ c:irua:126032 Serial 1048
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Author van den Broek, B.; Houssa, M.; Scalise, E.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Two-dimensional hexagonal tin : ab initio geometry, stability, electronic structure and functionalization Type A1 Journal article
Year 2014 Publication 2D materials Abbreviated Journal 2D Mater
Volume 1 Issue Pages 021004
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We study the structural, mechanical and electronic properties of the two-dimensional (2D) allotrope of tin: tinene/stanene using first-principles calculation within density functional theory, implemented in a set of computer codes. Continuing the trend of the group-IV 2D materials graphene, silicene and germanene; tinene is predicted to have a honeycomb lattice with lattice parameter of a(0) = 4.62 angstrom and a buckling of d(0) = 0.92 angstrom. The electronic dispersion shows a Dirac cone with zero gap at the Fermi energy and a Fermi velocity of v(F) = 0.97 x 10(6) m s(-1); including spin-orbit coupling yields a bandgap of 0.10 eV. The monolayer is thermally stable up to 700 K, as indicated by first-principles molecular dynamics, and has a phonon dispersion without imaginary frequencies. We explore applied electric field and applied strain as functionalization mechanisms. Combining these two mechanisms allows for an induced bandgap up to 0.21 eV, whilst retaining the linear dispersion, albeit with degraded electronic transport parameters.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication (down) Bristol Editor
Language Wos 000353650400004 Publication Date 2014-08-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 58 Open Access
Notes Approved Most recent IF: 6.937; 2014 IF: NA
Call Number UA @ lucian @ c:irua:134432 Serial 4530
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Author van den Broek, B.; Houssa, M.; Iordanidou, K.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Functional silicene and stanene nanoribbons compared to graphene: electronic structure and transport Type A1 Journal article
Year 2016 Publication 2D materials Abbreviated Journal 2D Mater
Volume 3 Issue 1 Pages 015001
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Since the advent of graphene, other 2D materials have garnered interest; notably the single element materials silicene, germanene, and stanene. Weinvestigate the ballistic current-voltage (I-V) characteristics of armchair silicene and stanene armchair nanoribbons (AXNRs with X = Si, Sn) using a combination of density functional theory and non-equilibrium Green's functions. The impact of out-of-plane electric field and in-plane uniaxial strain on the ribbon geometries, electronic structure, and (I-V)s are considered and contrasted with graphene. Since silicene and stanene are sp(2)/sp(3) buckled layers, the electronic structure can be tuned by an electric field that breaks the sublattice symmetry, an effect absent in graphene. This decreases the current by similar to 50% for Sn, since it has the largest buckling. Uniaxial straining of the ballistic channel affects the AXNR electronic structure in multiple ways: it changes the bandgap and associated effective carrier mass, and creates a local buckling distortion at the lead-channel interface which induces a interface dipole. Due to the increasing sp(3) hybridization character with increasing element mass, large reconstructions rectify the strained systems, an effect absent in sp(2) bonded graphene. This results in a smaller strain effect on the current: a decrease of 20% for Sn at 15% tensile strain compared to a similar to 75% decrease for C.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication (down) Bristol Editor
Language Wos 000373936300021 Publication Date 2016-01-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 19 Open Access
Notes Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:144746 Serial 4658
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Author van den Broek, B.; Houssa, M.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Current-voltage characteristics of armchair Sn nanoribbons Type A1 Journal article
Year 2014 Publication Physica status solidi: rapid research letters Abbreviated Journal Phys Status Solidi-R
Volume 8 Issue 11 Pages 931-934
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Two-dimensional group-IV lattices silicene and germanene are known to share many of graphene's remarkable mechanical and electronic properties. Due to the out-of-plane buckling of the former materials, there are more means of electronic funtionalization, e.g. by applying uniaxial strain or an out-of-plane electric field. We consider monolayer hexagonal Sn (stanene) as an ideal candidate to feasibly implement and exploit graphene physics for nanoelectronic applications: with increased out-of-plane buckling and sizable spin-orbit coupling it lends itself to improved Dirac cone engineering. We investigate the ballistic charge transport regime of armchair Sn nanoribbons, classified according to the ribbon width W = {3m – 1, 3m, 3m + 1} with integer m. We study transport through (non-magnetic) armchair ribbons using a combination of density functional theory and non-equilibrium Green's functions. Sn ribbons have earlier current onsets and carry currents 20% larger than C/Si/Ge-nanoribbons as the contact resistance of these ribbons is found to be comparable. ((c) 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
Address
Corporate Author Thesis
Publisher Place of Publication (down) Berlin Editor
Language Wos 000345274300009 Publication Date 2014-09-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1862-6254; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.032 Times cited 9 Open Access
Notes Approved Most recent IF: 3.032; 2014 IF: 2.142
Call Number UA @ lucian @ c:irua:122148 Serial 594
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Author Clima, S.; Sankaran, K.; Chen, Y.Y.; Fantini, A.; Celano, U.; Belmonte, A.; Zhang, L.; Goux, L.; Govoreanu, B.; Degraeve, R.; Wouters, D.J.; Jurczak, M.; Vandervorst, W.; Gendt, S.D.; Pourtois, G.;
Title RRAMs based on anionic and cationic switching : a short overview Type A1 Journal article
Year 2014 Publication Physica status solidi: rapid research letters Abbreviated Journal Phys Status Solidi-R
Volume 8 Issue 6 Pages 501-511
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Resistive random access memories are emerging as a new type of memory that has the potential to combine both the speed of volatile and the retention of nonvolatile memories. It operates based on the formation/dissolution of a low-resistivity filament being constituted of either metallic ions or atomic vacancies within an insulating matrix. At present, the mechanisms and the parameters controlling the performances of the device remain unclear. In that respect, first-principles simulations provide useful insights on the atomistic mechanisms, the thermodynamic and kinetics factors that modulate the material conductivity, providing guidance into the engineering of the operation of the device. In this paper, we review the current state-of-the-art knowledge on the atomistic switching mechanisms driving the operation of copper-based conductive bridge RRAM and HfOx valence change RRAM. [GRAPHICS] Conceptual illustration of the RRAM device with the filament formation and disruption during its operation. AE/IM/CE are the active electrode/insulating matrix/counterelectrode. The blue circles represent the conducting defects. (C) 2014 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim
Address
Corporate Author Thesis
Publisher Place of Publication (down) Berlin Editor
Language Wos 000338021200004 Publication Date 2014-04-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1862-6254; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.032 Times cited 28 Open Access
Notes Approved Most recent IF: 3.032; 2014 IF: 2.142
Call Number UA @ lucian @ c:irua:118679 Serial 2933
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Author Pourtois, G.; Lauwers, A.; Kittl, J.; Pantisano, L.; Sorée, B.; De Gendt, S.; Magnus, W.; Heyns, A.; Maex, K.
Title First-principle calculations on gate/dielectric interfaces : on the origin of work function shifts Type A1 Journal article
Year 2005 Publication Microelectronic engineering Abbreviated Journal Microelectron Eng
Volume 80 Issue Pages 272-279
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The impact of interfacial chemistry occurring at dielectric/gate interface of P-MOS and N-MOS devices is reviewed through a quick literature survey. A specific emphasis is put on the way the bond polarization that occurs between a dielectric and a metal substrate impacts on the gate work function. First-principle simulations are then used to study the work function changes induced by dopant aggregation in nickel monosilicide metal gates. It is shown that the changes are a natural consequence of the variation of the interface polarization.
Address
Corporate Author Thesis
Publisher Place of Publication (down) Amsterdam Editor
Language Wos 000231517000062 Publication Date 2005-06-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0167-9317; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.806 Times cited 31 Open Access
Notes Approved Most recent IF: 1.806; 2005 IF: 1.347
Call Number UA @ lucian @ c:irua:95095 Serial 1199
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