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Author Scarrozza, M.; Pourtois, G.; Houssa, M.; Heyns, M.; Stesmans, A.
Title Oxidation of the GaAs(001) surface : insights from first-principles calculations Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 85 Issue 19 Pages 195307-195307,8
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We performed a detailed investigation of the oxidation of the technologically relevant GaAs(001)-beta 2(2x4) surface via density functional calculations. The purpose is to gain insights on the atomistic mechanisms and local bondings that underlie the degradation of the surface properties once exposed to oxygen. The study comprises the adsorption of single O atoms, through the sampling of several adsorption sites, and the subsequent formation of the O adsorbate at increasing coverage by taking into account multiple-atom adsorption. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results here reported delineate a consistent picture of the initial stage of the surface oxidation: (i) at low coverage, in the limit of single O insertions, oxygen is incorporated on the surface forming a twofold-bridging Ga-O-As bond; (ii) at increasing coverage, as multiple O atoms are involved, this is accompanied by the formation of a threefold-coordinated bond (with two Ga and one As atoms); (iii) the latter has important implications regarding the electronic properties of the adsorbate since this O bonding may result in the formation of As dangling bonds. Moreover, a clear trend of increased energy gain for the incorporation of neighboring O atoms compared to single O insertions indicates that the formation of oxide clusters is favored over a regime of uniform oxidation. Our findings provide a detailed description of the O bonding and stress the importance of modeling the adsorption of multiple O atoms for an accurate description of the surface oxidation.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000303755700006 Publication Date 2012-05-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 15 Open Access
Notes Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:99122 Serial 2538
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Author Neyts, E.C.; Thijsse, B.J.; Mees, M.J.; Bal, K.M.; Pourtois, G.
Title Establishing uniform acceptance in force biased Monte Carlo simulations Type A1 Journal article
Year 2012 Publication Journal of chemical theory and computation Abbreviated Journal J Chem Theory Comput
Volume 8 Issue 6 Pages 1865-1869
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Uniform acceptance force biased Monte Carlo (UFMC) simulations have previously been shown to be a powerful tool to simulate atomic scale processes, enabling one to follow the dynamical path during the simulation. In this contribution, we present a simple proof to demonstrate that this uniform acceptance still complies with the condition of detailed balance, on the condition that the characteristic parameter lambda = 1/2 and that the maximum allowed step size is chosen to be sufficiently small. Furthermore, the relation to Metropolis Monte Carlo (MMC) is also established, and it is shown that UFMC reduces to MMC by choosing the characteristic parameter lambda = 0 [Rao, M. et al. Mol. Phys. 1979, 37, 1773]. Finally, a simple example compares the UFMC and MMC methods.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000305092400002 Publication Date 2012-05-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1549-9618;1549-9626; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 5.245 Times cited 20 Open Access
Notes Approved Most recent IF: 5.245; 2012 IF: 5.389
Call Number UA @ lucian @ c:irua:99090 Serial 1082
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Author Khalilov, U.; Pourtois, G.; van Duin, A.C.T.; Neyts, E.C.
Title Self-limiting oxidation in small-diameter Si nanowires Type A1 Journal article
Year 2012 Publication Chemistry of materials Abbreviated Journal Chem Mater
Volume 24 Issue 11 Pages 2141-2147
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Recently, core shell silicon nanowires (Si-NWs) have been envisaged to be used for field-effect transistors and photovoltaic applications. In spite of the constant downsizing of such devices, the formation of ultrasmall diameter core shell Si-NWs currently remains entirely unexplored. We report here on the modeling of the formation of such core shell Si-NWs using a dry thermal oxidation of 2 nm diameter (100) Si nanowires at 300 and 1273 K, by means of reactive molecular dynamics simulations using the ReaxFF potential. Two different oxidation mechanisms are discussed, namely a self-limiting process that occurs at low temperature (300 K), resulting in a Si core I ultrathin SiO2 silica shell nanowire, and a complete oxidation process that takes place at a higher temperature (1273 K), resulting in the formation of an ultrathin SiO2 silica nanowire. The oxidation kinetics of both cases and the resulting structures are analyzed in detail. Our results demonstrate that precise control over the Si-core radius of such NWs and the SiOx (x <= 2.0) oxide shell is possible by controlling the growth temperature used during the oxidation process.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000305092600021 Publication Date 2012-05-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0897-4756;1520-5002; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 9.466 Times cited 45 Open Access
Notes Approved Most recent IF: 9.466; 2012 IF: 8.238
Call Number UA @ lucian @ c:irua:99079 Serial 2976
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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]
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication 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 (down) 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 Khalilov, U.; Pourtois, G.; van Duin, A.C.T.; Neyts, E.C.
Title Hyperthermal oxidation of Si(100)2x1 surfaces : effect of growth temperature Type A1 Journal article
Year 2012 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 116 Issue 15 Pages 8649-8656
Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Using reactive molecular dynamics simulations based on the ReaxFF potential, we studied the growth mechanism of ultrathin silica (SiO2) layers during hyperthermal oxidation as a function of temperature in the range 100-1300 K. Oxidation of Si(100){2 x 1} surfaces by both atomic and molecular oxygen was investigated for hyperthermal impact energies in the range of 1 to 5 eV. Two different growth mechanisms are found, corresponding to a low temperature oxidation and a high temperature one. The transition temperature between these mechanisms is estimated to be about 700 K. Also, the initial step of the Si oxidation process is analyzed in detail. Where possible, we validated our results with experimental and ab initio data, and good agreement was obtained. This study is important for the fabrication of silica-based devices in the micro- and nanoelectronics industry and, more specifically, for the fabrication of metal oxide semiconductor devices.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000302924900035 Publication Date 2012-03-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 32 Open Access
Notes Approved Most recent IF: 4.536; 2012 IF: 4.814
Call Number UA @ lucian @ c:irua:98259 Serial 1542
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Author Pham, A.-T.; Sorée, B.; Magnus, W.; Jungemann, C.; Meinerzhagen, B.; Pourtois, G.
Title Quantum simulations of electrostatics in Si cylindrical junctionless nanowire nFETs and pFETs with a homogeneous channel including strain and arbitrary crystallographic orientations Type A1 Journal article
Year 2012 Publication Solid state electronics Abbreviated Journal Solid State Electron
Volume 71 Issue Pages 30-36
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Simulation results of electrostatics in Si cylindrical junctionless nanowire transistors with a homogenous channel are presented. Junctionless transistors including strain and arbitrary crystallographic orientations are studied. Size quantization effects are simulated by self-consistent solutions of the Poisson and Schrodinger equations. The 6 x 6 k.p method is employed for the calculation of the valence subband structure in a junctionless nanowire pFET. The influence of stress/strain and crystallographic channel orientation on to the electrostatics in terms of subband structure, charge density, and C-V curve is systematically studied. (C) 2011 Elsevier Ltd. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000303033800007 Publication Date 2011-12-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0038-1101; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 1.58 Times cited 2 Open Access
Notes ; ; Approved Most recent IF: 1.58; 2012 IF: 1.482
Call Number UA @ lucian @ c:irua:98245 Serial 2786
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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.
Address
Corporate Author Thesis
Publisher Place of Publication 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 (down) 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 Clima, S.; Chen, Y.Y.; Degraeve, R.; Mees, M.; Sankaran, K.; Govoreanu, B.; Jurczak, M.; De Gendt, S.; Pourtois, G.
Title First-principles simulation of oxygen diffusion in HfOx : role in the resistive switching mechanism Type A1 Journal article
Year 2012 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 100 Issue 13 Pages 133102-133102,4
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Transition metal oxide-based resistor random access memory (RRAM) takes advantage of oxygen-related defects in its principle of operation. Since the change in resistivity of the material is controlled by the oxygen deficiency level, it is of major importance to quantify the kinetics of the oxygen diffusion, key factor for oxide stoichiometry. Ab initio accelerated molecular dynamics techniques are employed to investigate the oxygen diffusivity in amorphous hafnia (HfOx, x = 1.97, 1.0, 0.5). The computed kinetics is in agreement with experimental measurements. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697690]
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000302230800060 Publication Date 2012-03-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 63 Open Access
Notes Approved Most recent IF: 3.411; 2012 IF: 3.794
Call Number UA @ lucian @ c:irua:97786 Serial 1214
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Author Mees, M.J.; Pourtois, G.; Neyts, E.C.; Thijsse, B.J.; Stesmans, A.
Title Uniform-acceptance force-bias Monte Carlo method with time scale to study solid-state diffusion Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 85 Issue 13 Pages 134301-134301,9
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Monte Carlo (MC) methods have a long-standing history as partners of molecular dynamics (MD) to simulate the evolution of materials at the atomic scale. Among these techniques, the uniform-acceptance force-bias Monte Carlo (UFMC) method [ G. Dereli Mol. Simul. 8 351 (1992)] has recently attracted attention [ M. Timonova et al. Phys. Rev. B 81 144107 (2010)] thanks to its apparent capacity of being able to simulate physical processes in a reduced number of iterations compared to classical MD methods. The origin of this efficiency remains, however, unclear. In this work we derive a UFMC method starting from basic thermodynamic principles, which leads to an intuitive and unambiguous formalism. The approach includes a statistically relevant time step per Monte Carlo iteration, showing a significant speed-up compared to MD simulations. This time-stamped force-bias Monte Carlo (tfMC) formalism is tested on both simple one-dimensional and three-dimensional systems. Both test-cases give excellent results in agreement with analytical solutions and literature reports. The inclusion of a time scale, the simplicity of the method, and the enhancement of the time step compared to classical MD methods make this method very appealing for studying the dynamics of many-particle systems.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000302290500001 Publication Date 2012-04-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 31 Open Access
Notes Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:97160 Serial 3809
Permanent link to this record
 
 
Author Scalise, E.; Houssa, M.; Pourtois, G.; Afanas'ev, V.; Stesmans, A.
Title Strain-induced semiconductor to metal transition in the two-dimensional honeycomb structure of MoS2 Type A1 Journal article
Year 2012 Publication Nano Research Abbreviated Journal Nano Res
Volume 5 Issue 1 Pages 43-48
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The electronic properties of two-dimensional honeycomb structures of molybdenum disulfide (MoS(2)) subjected to biaxial strain have been investigated using first-principles calculations based on density functional theory. On applying compressive or tensile bi-axial strain on bi-layer and mono-layer MoS(2), the electronic properties are predicted to change from semiconducting to metallic. These changes present very interesting possibilities for engineering the electronic properties of two-dimensional structures of MoS(2).
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000299085200006 Publication Date 2011-11-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1998-0124;1998-0000; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 7.354 Times cited 407 Open Access
Notes Approved Most recent IF: 7.354; 2012 IF: 7.392
Call Number UA @ lucian @ c:irua:96262 Serial 3169
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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]
Address
Corporate Author Thesis
Publisher Place of Publication 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 (down) 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 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 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 (down) 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
Permanent link to this record
 
 
Author Khalilov, U.; Neyts, E.C.; Pourtois, G.; van Duin, A.C.T.
Title Can we control the thickness of ultrathin silica layers by hyperthermal silicon oxidation at room temperature? Type A1 Journal article
Year 2011 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 115 Issue 50 Pages 24839-24848
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Using reactive molecular dynamics simulations by means of the ReaxFF potential, we studied the growth mechanism of ultrathin silica (SiO2) layers during hyperthermal oxidation at room temperature. Oxidation of Si(100){2 × 1} surfaces by both atomic and molecular oxygen was investigated in the energy range 15 eV. The oxidation mechanism, which differs from thermal oxidation, is discussed. In the case of oxidation by molecular O2, silica is quickly formed and the thickness of the formed layers remains limited compared to oxidation by atomic oxygen. The Si/SiO2 interfaces are analyzed in terms of partial charges and angle distributions. The obtained structures of the ultrathin SiO2 films are amorphous, including some intrinsic defects. This study is important for the fabrication of silica-based devices in the micro- and nanoelectronics industry, and more specifically for the fabrication of metal oxide semiconductor devices.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000297947700050 Publication Date 2011-11-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 36 Open Access
Notes Approved Most recent IF: 4.536; 2011 IF: 4.805
Call Number UA @ lucian @ c:irua:94303 Serial 273
Permanent link to this record
 
 
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.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication 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 (down) 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 Pham, A.-T.; Zhao, Q.-T.; Jungemann, C.; Meinerzhagen, B.; Mantl, S.; Sorée, B.; Pourtois, G.
Title Comparison of strained SiGe heterostructure-on-insulator (0 0 1) and (1 1 0) PMOSFETs : CV characteristics, mobility, and ON current Type A1 Journal article
Year 2011 Publication Solid state electronics Abbreviated Journal Solid State Electron
Volume 65-66 Issue Pages 64-71
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Strained SiGe heterostructure-on-insulator (0 0 1) and (1 1 0) PMOSFETs are investigated including important aspects like CV characteristics, mobility, and ON current. The simulations are based on the self-consistent solution of 6 × 6 k · p Schrödinger Equation, multi subband Boltzmann Transport Equation and Poisson Equation, and capture size quantization, strain, crystallographic orientation, and SiGe alloy effects on a solid physical basis. The simulation results are validated by comparison with different experimental data sources. The simulation results show that the strained SiGe HOI PMOSFET with (1 1 0) surface orientation has a higher gate capacitance and a much higher mobility and ON current compared to a similar device with the traditional (0 0 1) surface orientation.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000297182700012 Publication Date 2011-07-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0038-1101; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 1.58 Times cited 2 Open Access
Notes ; ; Approved Most recent IF: 1.58; 2011 IF: 1.397
Call Number UA @ lucian @ c:irua:92866 Serial 433
Permanent link to this record
 
 
Author Houssa, M.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Electronic properties of two-dimensional hexagonal germanium Type A1 Journal article
Year 2010 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 96 Issue 8 Pages 082111,1-082111,3
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The electronic properties of two-dimensional hexagonal germanium, so called germanene, are investigated using first-principles simulations. Consistent with previous reports, the surface is predicted to have a poor metallic behavior, i.e., being metallic with a low density of states at the Fermi level. It is found that biaxial compressively strained germanene is a gapless semiconductor with linear energy dispersions near the K pointslike graphene. The calculated Fermi velocity of germanene is almost independent of the strain and is about 1.7×10<sup>6</sup> m/s, quite comparable to the value in graphene.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000275027200044 Publication Date 2010-02-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 86 Open Access
Notes Approved Most recent IF: 3.411; 2010 IF: 3.841
Call Number UA @ lucian @ c:irua:91716 Serial 1004
Permanent link to this record
 
 
Author Nourbakhsh, A.; Cantoro, M.; Klekachev, A.V.; Pourtois, G.; Vosch, T.; Hofkens, J.; van der Veen, M.H.; Heyns, M.M.; de Gendt, S.; Sels, B.F.
Title Single layer vs bilayer graphene : a comparative study of the effects of oxygen plasma treatment on their electronic and optical properties Type A1 Journal article
Year 2011 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 115 Issue 33 Pages 16619-16624
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract This contribution presents the effects of a mild O2 plasma treatment on the structural, optical, and electrical properties of single-layer (SLG) and bilayer graphene (BLG). Unexpectedly, we observe only photoluminescence in the SLG parts of a graphene flake composed of regions of various thickness upon O2 plasma treatment, whereas the BLG and few-layer graphene (FLG) parts remain optically unchanged. Confirmed with X-ray photoelectron spectroscopy (XPS) that O2 plasma induces epoxide and hydroxyl-like groups in graphene, density functional theory (DFT) calculations are carried out on representative epoxidized and hydroxylated SLG and BLG models to predict density of states (DOS) and band structures. Sufficiently oxidized SLG shows a bandgap and thus loss of semimetallic behavior, while oxidized BLG maintains its semimetallic behavior even at high oxygen density in agreement with the results of the photoluminescence spectroscopy (PL) experiments. DFT calculations confirm that the Fermi velocity in epoxidized BLG is remarkably comparable with that of pristine SLG, pointing to a similarity of electronic band structure. The similarity is also experimentally demonstrated by the electrical characterization of a plasma-treated BLG-FET. As expected from the electronegative oxygen adatoms in the graphene, epoxidized BLG presents conductive features typical of hole doping. Moreover, the electrical characteristics suggest band structures closely related to that of epoxidized graphene while deviating from that of hydroxylated graphene. Finally, upon O2 plasma treatment of BLG, the four-component 2D peak around 2700 cm1 in the Raman spectrum evolves into a single Lorentzian line, very like the 2D peak of pristine SLG. Summarizing, the data in this contribution recommend that a controlled O2 plasma treatment, which is compatible with CMOS process flow in contrast to wet chemical oxidation methods, provides an efficient and valuable technique to exploit the transport properties of the bottom layer of BLG.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000294077000047 Publication Date 2011-06-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 46 Open Access
Notes Approved Most recent IF: 4.536; 2011 IF: 4.805
Call Number UA @ lucian @ c:irua:91715 Serial 3024
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Author Delabie, A.; Sioncke, S.; Rip, J.; van Elshocht, S.; Caymax, M.; Pourtois, G.; Pierloot, K.
Title Mechanisms for the trimethylaluminum reaction in aluminum oxide atomic layer deposition on sulfur passivated germanium Type A1 Journal article
Year 2011 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 115 Issue 35 Pages 17523-17532
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Germanium combined with high-κ dielectrics is investigated for the next generations of CMOS devices. Therefore, we study reaction mechanisms for Al2O3 atomic layer deposition on sulfur passivated Ge using calculations based on density functional theory and total reflection X-ray fluorescence (TXRF). TXRF indicates 6 S/nm2 and 4 Al/nm2 after the first TMA/H2O reaction cycle, and growth inhibition from the second reaction cycle on. Calculations are performed on molecular clusters representing −GeSH surface sites. The calculations confirm that the TMA reaction does not affect the S content. On fully SH-terminated Ge, TMA favorably reacts with up to three −GeSH sites, resulting in a near tetrahedral Al coordination. Electron deficient structures with a GeS site shared between two Al atoms are proposed. The impact of the cluster size on the structures and reaction energetics is systematically investigated.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000294386000037 Publication Date 2011-08-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 9 Open Access
Notes Approved Most recent IF: 4.536; 2011 IF: 4.805
Call Number UA @ lucian @ c:irua:91714 Serial 1980
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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.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication 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 (down) 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 Neyts, E.C.; Khalilov, U.; Pourtois, G.; van Duin, A.C.T.
Title Hyperthermal oxygen interacting with silicon surfaces : adsorption, implantation, and damage creation Type A1 Journal article
Year 2011 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal J Phys Chem C
Volume 115 Issue 15 Pages 4818-4823
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Using reactive molecular dynamics simulations, we have investigated the effect of single-impact, low-energy (thermal-100 eV) bombardment of a Si(100){2 × 1} surface by atomic and molecular oxygen. Penetration probability distributions, as well as defect formation distributions, are presented as a function of the impact energy for both species. It is found that at low impact energy, defects are created chemically due to the chemisorption process in the top layers of the surface, while at high impact energy, additional defects are created by a knock-on displacement of Si. These results are of particular importance for understanding device performances of silica-based microelectronic and photovoltaic devices.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000288401200060 Publication Date 2011-03-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 28 Open Access
Notes Approved Most recent IF: 4.536; 2011 IF: 4.805
Call Number UA @ lucian @ c:irua:89858 Serial 1543
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Author Sorée, B.; Magnus, W.; Pourtois, G.
Title Analytical and self-consistent quantum mechanical model for a surrounding gate MOS nanowire operated in JFET mode Type A1 Journal article
Year 2008 Publication Journal of computational electronics Abbreviated Journal J Comput Electron
Volume 7 Issue 3 Pages 380-383
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We derive an analytical model for the electrostatics and the drive current in a silicon nanowire operating in JFET mode. We show that there exists a range of nanowire radii and doping densities for which the nanowire JFET satisfies reasonable device characteristics. For thin nanowires we have developed a self-consistent quantum mechanical model to obtain the electronic structure.
Address
Corporate Author Thesis
Publisher Place of Publication S.l. Editor
Language Wos 000208473800067 Publication Date 2008-02-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1569-8025;1572-8137; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 1.526 Times cited 70 Open Access
Notes Approved Most recent IF: 1.526; 2008 IF: NA
Call Number UA @ lucian @ c:irua:89504 Serial 107
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Author Neyts, E.; Maeyens, A.; Pourtois, G.; Bogaerts, A.
Title A density-functional theory simulation of the formation of Ni-doped fullerenes by ion implantation Type A1 Journal article
Year 2011 Publication Carbon Abbreviated Journal Carbon
Volume 49 Issue 3 Pages 1013-1017
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Using self-consistent KohnSham density-functional theory molecular dynamics simulations, we demonstrate the theoretical possibility to synthesize NiC60, the incarfullerene Ni@C60 and the heterofullerene C59Ni in an ion implantation setup. The corresponding formation mechanisms of all three complexes are elucidated as a function of the ion implantation energy and impact location, suggesting possible routes for selectively synthesizing these complexes.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000286683500032 Publication Date 2010-11-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0008-6223; ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 6.337 Times cited 13 Open Access
Notes Approved Most recent IF: 6.337; 2011 IF: 5.378
Call Number UA @ lucian @ c:irua:85139 Serial 639
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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
Address
Corporate Author Thesis
Publisher Place of Publication 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 (down) 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 Clima, S.; O'Sullivan, B.J.; Ronchi, N.; Bardon, M.G.; Banerjee, K.; Van den Bosch, G.; Pourtois, G.; van Houdt, J.
Title Ferroelectric switching in FEFET : physics of the atomic mechanism and switching dynamics in HfZrOx, HfO2 with oxygen vacancies and Si dopants Type P1 Proceeding
Year 2020 Publication Abbreviated Journal
Volume Issue Pages
Keywords P1 Proceeding; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The fine balance between dipole-field energy and anion drift force defines the switching mechanism during polarization reversal: for the first time we show that only Pbcm mechanism obeys the ferroelectric switching physics, whereas P4(2)/nmc (or any other) mechanism does not. However, with lower energy barrier, it represents an important antiferroelectric mechanism. Constraints relaxation can lead to 90 degrees polarization rotation (domain deactivation). Intrinsically, the Si/VO-doping can switch faster than undoped HfO2 or HfZrOx. Theoretical Arrhenius model / intrinsic material switching (DFT) overestimates the switching speed extracted from experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000717011600218 Publication Date 2021-03-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 978-1-7281-8888-1 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:184730 Serial 7963
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Author Guo, J.; Clima, S.; Pourtois, G.; Van Houdt, J.
Title Identifying alternative ferroelectric materials beyond Hf(Zr)O-₂ Type A1 Journal article
Year 2020 Publication Applied Physics Letters Abbreviated Journal Appl Phys Lett
Volume 117 Issue 26 Pages 262903
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract A database-driven approach combined with ab initio density functional theory (DFT) simulations is used to identify and simulate alternative ferroelectric materials beyond Hf(Zr)O-2. The database-driven screening method identifies a class of wurtzite ferroelectric materials. DFT simulations of wurtzite magnesium chalcogenides, including MgS, MgSe, and MgTe, show their potential to achieve improved ferroelectric (FE) stability, simple atomistic unit cell structure, and large FE polarization. Strain engineering can effectively modulate the FE switching barrier height for facilitating FE switching. The effect of the piezoelectric property on the FE switching barrier heights is also examined.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000608049700003 Publication Date 2020-12-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; 1077-3118 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 4 Times cited Open Access
Notes Approved Most recent IF: 4; 2020 IF: 3.411
Call Number UA @ admin @ c:irua:176053 Serial 6766
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Author Khanam, A.; Vohra, A.; Slotte, J.; Makkonen, I.; Loo, R.; Pourtois, G.; Vandervorst, W.
Title A demonstration of donor passivation through direct formation of V-As-i complexes in As-doped Ge1-XSnx Type A1 Journal article
Year 2020 Publication Journal Of Applied Physics Abbreviated Journal J Appl Phys
Volume 127 Issue 19 Pages 195703
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Positron annihilation spectroscopy in the Doppler and coincidence Doppler mode was applied on Ge1 xSnx epitaxial layers, grown by chemical vapor deposition with different total As concentrations (1019-1021 cm3), high active As concentrations (1019 cm3), and similar Sn concentrations (5.9%-6.4%). Positron traps are identified as mono-vacancy complexes. Vacancy-As complexes, V-Asi, formed during the growth were studied to deepen the understanding of the electrical passivation of the Ge1 xSnx:As epilayers. Larger monovacancy complexes, V-Asi (i 2), are formed as the As doping increases. The total As concentration shows a significant impact on the saturation of the number of As atoms (i 1/4 4) around the vacancies in the sample epilayers. The presence of V-Asi complexes decreases the dopant activation in the Ge1 xSnx:As epilayers. Furthermore, the presence of Sn failed to hinder the formation of larger V-Asi complexes and thus failed to reduce the donor-deactivation.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000536196000003 Publication Date 2020-05-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; 1089-7550 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.2 Times cited Open Access
Notes ; ; Approved Most recent IF: 3.2; 2020 IF: 2.068
Call Number UA @ admin @ c:irua:170252 Serial 6447
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Author Vohra, A.; Makkonen, I.; Pourtois, G.; Slotte, J.; Porret, C.; Rosseel, E.; Khanam, A.; Tirrito, M.; Douhard, B.; Loo, R.; Vandervorst, W.
Title Source/drain materials for Ge nMOS devices: phosphorus activation in epitaxial Si, Ge, Ge1-xSnx and SiyGe1-x-ySnx Type A1 Journal article
Year 2020 Publication Ecs Journal Of Solid State Science And Technology Abbreviated Journal Ecs J Solid State Sc
Volume 9 Issue 4 Pages 044010-44012
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract This paper benchmarks various epitaxial growth schemes based on n-type group-IV materials as viable source/drain candidates for Ge nMOS devices. Si:P grown at low temperature on Ge, gives an active carrier concentration as high as 3.5 x 10(20) cm(-3) and a contact resistivity down to 7.5 x 10(-9) Omega.cm(2). However, Si:P growth is highly defective due to large lattice mismatch between Si and Ge. Within the material stacks assessed, one option for Ge nMOS source/drain stressors would be to stack Si:P, deposited at contact level, on top of a selectively grown n-SiyGe1-x-ySnx at source/drain level, in line with the concept of Si passivation of n-Ge surfaces to achieve low contact resistivities as reported in literature (Martens et al. 2011 Appl. Phys. Lett., 98, 013 504). The saturation in active carrier concentration with increasing P (or As)-doping is the major bottleneck in achieving low contact resistivities for as-grown Ge or SiyGe1-x-ySnx. We focus on understanding various dopant deactivation mechanisms in P-doped Ge and Ge1-xSnx alloys. First principles simulation results suggest that P deactivation in Ge and Ge1-xSnx can be explained both by P-clustering and donor-vacancy complexes. Positron annihilation spectroscopy analysis, suggests that dopant deactivation in P-doped Ge and Ge1-xSnx is primarily due to the formation of P-n-V and SnmPn-V clusters. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000531473500002 Publication Date 2020-04-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2162-8769; 2162-8777 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 2.2 Times cited Open Access
Notes ; The imec core CMOS program members, European Commission, the TAKEMI5 ECSEL project, local authorities and the imec pilot line are acknowledged for their support. Air Liquide Advanced Materials is acknowledged for providing advanced precursor gases. A. V. acknowledges his long stay abroad grant and a grant for participation in congress abroad from the Research Foundation-Flanders (Application No. V410518N and K159219N). I. M. acknowledges financial support from Academy of Finland (Project Nos. 285 809, 293 932 and 319 178). CSC-IT Center for Science, Finland is acknowledged for providing the computational resources. ; Approved Most recent IF: 2.2; 2020 IF: 1.787
Call Number UA @ admin @ c:irua:169502 Serial 6607
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Author Mehta, A.N.; Mo, J.; Pourtois, G.; Dabral, A.; Groven, B.; Bender, H.; Favia, P.; Caymax, M.; Vandervorst, W.
Title Grain-boundary-induced strain and distortion in epitaxial bilayer MoS₂ lattice Type A1 Journal article
Year 2020 Publication Journal Of Physical Chemistry C Abbreviated Journal J Phys Chem C
Volume 124 Issue 11 Pages 6472-6478
Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Grain boundaries between 60 degrees rotated and twinned crystals constitute the dominant type of extended line defects in two-dimensional transition metal dichalcogenides (2D MX2) when grown on a single crystalline template through van der Waals epitaxy. The two most common 60 degrees grain boundaries in MX2 layers, i.e., beta- and gamma-boundaries, introduce distinct distortion and strain into the 2D lattice. They impart a localized tensile or compressive strain on the subsequent layer, respectively, due to van der Waals coupling in bilayer MX2 as determined by combining atomic resolution electron microscopy, geometric phase analysis, and density functional theory. Based on these observations, an alternate route to strain engineering through controlling intrinsic van der Waals forces in homobilayer MX2 is proposed. In contrast to the commonly used external means, this approach enables the localized application of strain to tune the electronic properties of the 2D semiconducting channel in ultra-scaled nanoelectronic applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000526396000067 Publication Date 2020-02-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447; 1932-7455 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited 2 Open Access
Notes ; ; Approved Most recent IF: 3.7; 2020 IF: 4.536
Call Number UA @ admin @ c:irua:168625 Serial 6528
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Author Clima, S.; Garbin, D.; Opsomer, K.; Avasarala, N.S.; Devulder, W.; Shlyakhov, I.; Keukelier, J.; Donadio, G.L.; Witters, T.; Kundu, S.; Govoreanu, B.; Goux, L.; Detavernier, C.; Afanas'ev, V.; Kar, G.S.; Pourtois, G.
Title Ovonic threshold-switching GexSey chalcogenide materials : stoichiometry, trap nature, and material relaxation from first principles Type A1 Journal article
Year 2020 Publication Physica Status Solidi-Rapid Research Letters Abbreviated Journal Phys Status Solidi-R
Volume Issue Pages 1900672
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Density functional theory simulations are used to identify the structural factors that define the material properties of ovonic threshold switches (OTS). They show that the nature of mobility-gap trap states in amorphous Ge-rich Ge50Se50 is related to Ge-Ge bonds, whereas in Se-rich Ge30Se70 the Ge valence-alternating-pairs and Se lone-pairs dominate. To obtain a faithful description of the electronic structure and delocalization of states, it is required to combine hybrid exchange-correlation functionals with large unit-cell models. The extent of localization of electronic states depends on the applied external electric field. Hence, OTS materials undergo structural changes during electrical cycling of the device, with a decrease in the population of less exothermic Ge-Ge bonds in favor of more exothermic Ge-Se. This reduces the amount of charge traps, which translates into coordination changes, an increase in mobility-gap, and subsequently changes in the selector-device electrical parameters. The threshold voltage drift process can be explained by natural evolution of the nonpreferred Ge-Ge bonds (or “chains”/clusters thereof) in Ge-rich GexSe1-x. The effect of extrinsic doping is shown for Si and N, which introduce strong covalent bonds into the system, increase both mobility-gap and crystallization temperature, and decrease the leakage current.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000512431100001 Publication Date 2020-01-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1862-6254 ISBN Additional Links (down) UA library record; WoS full record; WoS citing articles
Impact Factor 2.8 Times cited 3 Open Access
Notes ; This work was carried out in the framework of the imec Core CMOS-Emerging Memory Program. Financial support from EU H2020-NMBPTO-IND-2018 project “INTERSECT” (Grant No. 814487) is acknowledged. ; Approved Most recent IF: 2.8; 2020 IF: 3.032
Call Number UA @ admin @ c:irua:166492 Serial 6575
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Author Yu, H.; Schaekers, M.; Chew, S.A.; Eyeraert, J.-L.; Dabral, A.; Pourtois, G.; Horiguchi, N.; Mocuta, D.; Collaert, N.; De Meyer, K.
Title Titanium (germano-)silicides featuring 10-9 Ω.cm2 contact resistivity and improved compatibility to advanced CMOS technology Type P1 Proceeding
Year 2018 Publication 2018 18th International Workshop On Junction Technology (iwjt) Abbreviated Journal
Volume Issue Pages 80-84 T2 - 18th International Workshop on Junction
Keywords P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract uIn this work, we discuss three novel Ti (germano-)silicidation techniques featuring respectively the pre-contact amorphization implantation (PCAI), the TiSi co-deposition, and Ti atomic layer deposition (ALD). All three techniques form TiSix(Ge-y) contacts with ultralow contact resistivity (rho(c)) of (1-3)x10(-9) Omega.cm(2) on both highly doped n-Si and p-SiGe substrates: these techniques meet rho(c) requirement of 5-14 nm CMOS technology and feature unified CMOS contact solutions. We further discuss the compatibility of these techniques to the realistic CMOS transistor fabrication.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000502768600020 Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 978-1-5386-4511-6; 978-1-5386-4511-6 ISBN Additional Links (down) UA library record; WoS full record
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:165190 Serial 8673
Permanent link to this record