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“Probing the intrinsic limitations of the contact resistance of metal/semiconductor interfaces through atomistic simulations”. Pourtois G, Dabral A, Sankaran K, Magnus W, Yu H, de de Meux AJ, Lu AKA, Clima S, Stokbro K, Schaekers M, Houssa M, Collaert N, Horiguchi N, Semiconductors, Dielectrics, And Metals For Nanoelectronics 15: In Memory Of Samares Kar , 303 (2017). http://doi.org/10.1149/08001.0303ECST
Abstract: In this contribution, we report a fundamental study of the factors that set the contact resistivity between metals and highly doped semiconductors. We investigate the case of n-type doped Si contacted with amorphous TiSi combining first-principles calculations with Non-Equilibrium Green functions transport simulations. The intrinsic contact resistivity is found to saturate at similar to 2x10(-10) Omega.cm(2) with the doping concentration and sets an intrinsic limit to the ultimate contact resistance achievable for n-doped Si vertical bar amorphous-TiSi. This limit arises from the intrinsic properties of the semiconductor and of the metal such as their electron effective masses and Fermi energies. We illustrate that, in this regime, contacting metals with a heavy electron effective mass helps reducing the interface intrinsic contact resistivity.
Keywords: P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 1
DOI: 10.1149/08001.0303ECST
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“Self-consistent 30-band simulation approach for (non-)uniformly strained confined heterostructure tunnel field-effect transistors”. Verreck D, Verhulst AS, Van de Put ML, Sorée B, Magnus W, Collaert N, Mocuta A, Groeseneken G, Simulation of Semiconductor Processes and, Devices (SISPAD)AND DEVICES (SISPAD 2017) , 29 (2017)
Abstract: Heterostructures of III-V materials under a mechanical strain are being actively researched to enhance the performance of the tunnel field-effect transistor (TFET). In scaled III-V device structures, however, the interplay between the effects of strain and quantum confinement on the semiconductor band structure and hence the performance is highly non-trivial. We have therefore developed a computationally efficient quantum mechanical simulator Pharos, which enables self-consistent full-zone k.p-based simulations of III-V TFETs under a general non-uniform strain. We present the self-consistent procedure and demonstrate it on confined staggered bandgap GaAs0.5Sb0.5/In0.53Ga0.47As TFETs. We find a large performance degradation due to size-induced quantum confinement compared to non-confined devices. We show that some performance can be regained either by applying a uniform biaxial tensile strain or through the non-uniform strain profile at a lattice-mismatched heterostructure.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
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Saberi-Pouya S (2018) Many body properties in monolayer and doublelayer black phosphorus. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Impact of calibrated band-tails on the subthreshold swing of pocketed TFETs”. Bizindavyi J, Verhulst AS, Sorée B, Groeseneken G, Conference digest
T2 –, 76th Device Research Conference (DRC), JUN 24-27, 2018, Santa Barbara, CA (2018)
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
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Callewaert V (2018) Development and application of a non-local theory for the description of positron surface states. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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de Aquino BRCHT (2018) Carbon nanotubes and graphene based devices : from nanosensors to confined water. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Bekaert J (2018) Ab initio description of multicomponent superconductivity in bulk to atomically thin materials. 290 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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de Aquino BRCHT (2018) Carbon nanotubes and graphene based devices : from nanosensors to confined water. 161 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Mulkers J (2018) Confinement phenomena in chiral ferromagnetic films. 156 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Callewaert V (2018) Development and application of a non-local theory for the description of positron surface states. 151 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Flammia L (2018) Emergent phenomena in nanostructured quantum-confined superconducting films. 172 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Jelić, Ž, (2018) Emergent vortex phenomena in spatially and temporally modulated superconducting condensates. 181 p
Keywords: Doctoral thesis; Engineering sciences. Technology; Condensed Matter Theory (CMT)
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Ribeiro Gomes R (2018) The first order equations for the Ginzburg-Landau theory and the vortex states near a permalloy disk. 220 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Li L (2019) First-principles studies of novel two-dimensional dirac materials. 152 p
Keywords: Doctoral thesis; Engineering sciences. Technology; Condensed Matter Theory (CMT)
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Ghorbanfekr Kalashami H (2019) Graphene-based membranes and nanoconfined water : molecular dynamics simulation study. 243 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Impact of calibrated band-tails on the subthreshold swing of pocketed TFETs”. Bizindavyi J, Verhulst AS, Sorée B, Groeseneken G, Conference digest
T2 –, 76th Device Research Conference (DRC), JUN 24-27, 2018, Santa Barbara, CA (2018). http://doi.org/10.1109/DRC.2018.8442246
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
DOI: 10.1109/DRC.2018.8442246
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“Machine Learning for Fast Characterization of Magnetic Logic Devices”. Kaintura A, Foss K, Couckuyt I, Dhaene T, Zografos O, Vaysset A, Sorée B, (edaps 2018) (2018)
Abstract: Non-charge-based logic devices are promising candidates for future logic circuits. Interest in studying and developing these devices has grown dramatically in the past decade as they possess key advantages over conventional CMOS technology. Due to their novel designs, a large number of micromagnetic simulations are required to fully characterize the behavior of these devices. The number and complexity of these simulations place large computational requirements on device development. We use state-of-the-art machine learning techniques to expedite identification of their behavior. Several intelligent sampling strategies are combined with machine learning multi-class classification models. These techniques are applied to a recently developed exchange-driven magnetic logic scheme that utilizes direct exchange coupling as the main driver.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
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Saberi-Pouya S (2018) Many body properties in monolayer and doublelayer black phosphorus. 148 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Domingos JLC (2018) Study of colloidal systems of anisotropic magnetic particles. 114 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Van der Donck M (2019) Excitonic complexes in transition metal dichalcogenides and related materials. 224 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Exploiting the novel electronic and magnetic structure of C3Nvia functionalization and conformation”. Bafekry A, Stampfl C, Shayesteh SF, Peeters FM, Advanced Electronic Materials 5, 1900459 (2019). http://doi.org/10.1002/AELM.201900459
Abstract: 2D polyaniline, C3N, is of recent high interest due to its unusual properties and potential use in various technological applications. In this work, through systematic first-principles calculations, the atomic, electronic, and magnetic structure of C3N and the changes induced due to functionalization by the adsorption of hydrogen, oxygen, and fluorine, for different coverages and sites, as well as on formation of nanoribbons including the effect of adsorbed hydrogen and oxygen, and the effect of strain, are investigated. Among other interesting phenomena, for hydrogen adsorption, a semiconductor-to-topological insulator transition, where two Dirac-points appear around the Fermi level, as well as ferromagnetic ordering for both hydrogen and oxygen functionalization, is identified. Considering C3N nanoribbons, adsorption of H leads to significant changes in the electronic properties, such as transforming the structures from semiconductor to metallic. Furthermore, investigating the effect of strain on the physical properties, it is found that the band gap can be significantly altered and controlled. The present findings predict that a wide variation in the magnetic and electronic structure of C3N can be achieved by adatom functionalization and conformation indicating its high potential for use in various technological applications, ranging from catalysis, energy storage, and nanoelectronic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.193
Times cited: 39
DOI: 10.1002/AELM.201900459
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Vieira De Castro L (2019) Properties of quasi particles on two dimensional materials and related structures. 79 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Anđ,elković, M (2019) O(N) numerical methods for investigating graphene heterostructures and moiré patterns. 207 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Strain, electric-field and functionalization induced widely tunable electronic properties in MoS2/BC3, /C3N and / C3N4 van der Waals heterostructures”. Bafekry A, Stampfl C, Ghergherehchi M, Nanotechnology (Bristol. Print) , 295202 pp (2020). http://doi.org/10.1088/1361-6528/AB884E
Abstract: In this paper, the effect of BC3, C3N and C3N4BC(3) and MoS2/C(3)N4 heterostructures are direct semiconductors with band gaps of 0.4 and 1.74 eV, respectively, while MoS2/C3N is a metal. Furthermore, the influence of strain and electric field on the electronic structure of these van der Waals heterostructures is investigated. The MoS2/BC3 heterostructure, for strains larger than -4%, transforms it into a metal where the metallic character is maintained for strains larger than -6%. The band gap decreases with increasing strain to 0.35 eV (at +2%), while for strain (>+6%) a direct-indirect band gap transition is predicted to occur. For the MoS2/C3N heterostructure, the metallic character persists for all strains considered. On applying an electric field, the electronic properties of MoS2/C3N4 are modified and its band gap decreases as the electric field increases. Interestingly, the band gap reaches 30 meV at +0.8 V/angstrom, and with increase above +0.8 V/angstrom, a semiconductor-to-metal transition occurs. Furthermore, we investigated effects of semi- and full-hydrogenation of MoS2/C3N and we found that it leads to a metallic and semiconducting character, respectively.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Times cited: 19
DOI: 10.1088/1361-6528/AB884E
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“The electronic, optical, and thermoelectric properties of monolayer PbTe and the tunability of the electronic structure by external fields and defects”. Bafekry A, Stampfl C, Peeters FM, Physica Status Solidi B-Basic Solid State Physics , 2000182 (2020). http://doi.org/10.1002/PSSB.202000182
Abstract: First‐principles calculations, within the framework of density functional theory, are used to investigate the structural, electronic, optical, and thermoelectric properties of monolayer PbTe. The effect of layer thickness, electric field, strain, and vacancy defects on the electronic and magnetic properties is systematically studied. The results show that the bandgap decreases as the layer thickness increases from monolayer to bulk. With application of an electric field on bilayer PbTe, the bandgap decreases from 70 meV (0.2 V Å⁻¹) to 50 meV (1 V Å⁻¹) when including spin–orbit coupling (SOC). Application of uniaxial strain induces a direct‐to‐indirect bandgap transition for strain greater than +6%. In addition, the bandgap decreases under compressive biaxial strain (with SOC). The effect of vacancy defects on the electronic properties of PbTe is also investigated. Such vacancy defects turn PbTe into a ferromagnetic metal (single vacancy Pb) with a magnetic moment of 1.3 μB, and into an indirect semiconductor with bandgap of 1.2 eV (single Te vacancy) and 1.5 eV (double Pb + Te vacancy). In addition, with change of the Te vacancy concentration, a bandgap of 0.38 eV (5.55%), 0.43 eV (8.33%), and 0.46 eV (11.11%) is predicted.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.6
Times cited: 40
DOI: 10.1002/PSSB.202000182
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Bafekry A (2020) Investigation of the effects of defects and impurities on nanostructures consisting of Group IV and V elements using First-principles calculations. 126 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Conti S (2020) Multi-band superfluidity and BEC-BCS crossover in novel ultrathin materials. 123 p
Keywords: Doctoral thesis; Sociology; History; Condensed Matter Theory (CMT)
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“Oxygen vacancies in the single layer of Ti₂CO₂, MXene: effects of gating voltage, mechanical strain, and atomic impurities”. Bafekry A, Van Nguyen C, Stampfl C, Akgenc B, Ghergherehchi M, Physica Status Solidi B-Basic Solid State Physics , 2000343 (2020). http://doi.org/10.1002/PSSB.202000343
Abstract: Herein, using first-principles calculations the structural and electronic properties of the Ti(2)CO(2)MXene monolayer with and without oxygen vacancies are systematically investigated with different defect concentrations and patterns, including partial, linear, local, and hexagonal types. The Ti(2)CO(2)monolayer is found to be a semiconductor with a bandgap of 0.35 eV. The introduction of oxygen vacancies tends to increase the bandgap and leads to electronic phase transitions from nonmagnetic semiconductors to half-metals. Moreover, the semiconducting characteristic of O-vacancy Ti(2)CO(2)can be adjusted via electric fields, strain, and F-atom substitution. In particular, an electric field can be used to alter the nonmagnetic semiconductor of O-vacancy Ti(2)CO(2)into a magnetic one or into a half-metal, whereas the electronic phase transition from a semiconductor to metal can be achieved by applying strain and F-atom substitution. The results provide a useful guide for practical applications of O-vacancy Ti(2)CO(2)monolayers in nanoelectronic and spinstronic nanodevices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.6
DOI: 10.1002/PSSB.202000343
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Vanherck J (2020) Spontaneous and induced magnetisation in two-dimensional and bulk Heisenberg ferromagnets : a quantum mechanical treatment. 160 p
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Van der Waals heterostructures of MoS₂, and Janus MoSSe monolayers on graphitic boron-carbon-nitride (BC₃, C₃N, C₃N₄, and C₄N₃) nanosheets: a first-principles study”. Bafekry A, Yagmurcukardes M, Akgenc B, Ghergherehchi M, Nguyen C, Journal Of Physics D-Applied Physics , 1 (2020). http://doi.org/10.1088/1361-6463/AB876C
Abstract: In this work, we extensively investigate the structural and electronic properties of van der Waals heterostructures (HTs) constructed by MoS${2}$/$BC3$, MoS${2}$/$C3N$, MoS${2}$/$C3N4$, MoS${2}$/$C4N3$ and those using Janus MoSSe instead of MoS$2$ by performing density functional theory calculations. The electronic band structure calculations and the corresponding partial density of states reveal that the significant changes are driven by quite strong layer-layer interaction between the constitutive layers. Our results show that although all monolayers are semiconductors as free-standing layers, the MoS${2}$/$C3N$ and MoS${2}$/$C4N3$ bilayer HTs display metallic behavior as a consequence of transfer of charge carriers between two constituent layers. In addition, it is found that in MoSSe/$C3N$ bilayer HT, the degree of metallicity is affected by the interface chalcogen atom type when Se atoms are facing to $C3N$ layer, the overlap of the bands around the Fermi level is smaller. Moreover, the half-metallic magnetic $C4N3$ is shown to form magnetic half-metallic trilayer HT with MoS$2$ independent of the stacking sequence, i.e. whether it is sandwiched or two $C4N3$ layer encapsulate MoS$2$ layer. We further analyze the trilayer HTs in which MoS$2$ is encapsulated by two different monolayers and it is revealed that at least with one magnetic monolayer, it is possible to construct a magnetic trilayer. While the trilayer of $C4N3$/MoS${2}$/$BC3$ and $C4N3$/MoS${2}$/$C3N4$ exhibit half-metallic characteristics, $C4N3$/MoS${_2}$/$C3$N possesses a magnetic metallic ground state. Overall, our results reveal that holly structures of BCN crystals are suitable for heterostructure formation even over van der Waals type interaction which significantly changes electronic nature of the constituent layers.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
DOI: 10.1088/1361-6463/AB876C
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