Justin R. Weber

University of California, Santa Barbara

*This is an algorithmically generated author record based on publicly available information.

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University of California, Santa Barbara

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Intel (United States)

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Justin R. Weber has a total of 39 co-authors. Here are the top co-authors by number of shared publications:

Chris G. Van de Walle
University of California, Santa Barbara
17 shared publications
Anderson Janotti
Department of Materials Science and Engineering, University of Delaware 4 , Newark, Delaware 19716
13 shared publications
J. B. Varley
University of California 1 Department of Physics Santa Barbara, California 93106-9530, USA
4 shared publications
B. B. Buckley
University of California 1 Department of Physics Santa Barbara, California 93106-9530, USA
2 shared publications
Joel Basile Varley
Lawrence Livermore National Laboratory
2 shared publications
Roberto Fornari
Department of Mathematical, Physical and Computer Science, University of Parma, 43124 Parma, Italy
2 shared publications

Latest Publications

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Cited by 18
- 16 February 2024
- Published by AIP Publishing in Journal of Applied Physics
Dangling bonds, the charge neutrality level, and band alignment in semiconductors
by J. B. Varley, J. R. Weber, A. Janotti, C. G. Van de Walle
We present a systematic study of the electronic properties of dangling bonds (DBs) in a variety of semiconductors and examine the relationship between DBs and the charge neutrality level (CNL) in the context of band alignments of semiconductors. We use first-principles calculations based on density functional theory to assess the energetics of DBs in a set of diamond-structure group-IV and III–V or II–VI zinc-blende-structure semiconductors, considering both cation and anion-derived states. We examine the charge-state transition levels of DBs to assess whether they can serve as a CNL to align band structures, by comparing with offsets calculated from interface calculations. Our results show that this approach for evaluating the CNL yields quantitative results for band offsets and provides useful insights. We discuss the relation with alternative approaches for determination of CNLs based on branch-point energies or transition levels of interstitial hydrogen.
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- 16 February 2024
- Published by AIP Publishing in Journal of Applied Physics
Open Access
Dangling bonds, the charge neutrality level, and band alignment in semiconductors
by J. B. Varley, J. R. Weber, A. Janotti, C. G. Van de Walle
We present a systematic study of the electronic properties of dangling bonds (DBs) in a variety of semiconductors and examine the relationship between DBs and the charge neutrality level (CNL) in the context of band alignments of semiconductors. We use first-principles calculations based on density functional theory to assess the energetics of DBs in a set of diamond-structure group-IV and III–V or II–VI zinc-blende-structure semiconductors, considering both cation and anion-derived states. We examine the charge-state transition levels of DBs to assess whether they can serve as a CNL to align band structures, by comparing with offsets calculated from interface calculations. Our results show that this approach for evaluating the CNL yields quantitative results for band offsets and provides useful insights. We discuss the relation with alternative approaches for determination of CNLs based on branch-point energies or transition levels of interstitial hydrogen.
Cited by 18
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Cited by 78
- 14 October 2013
- Published by Springer Nature in MRS Bulletin
Quantum computing with defects
by Luke Gordon, Justin R. Weber, Joel B. Varley, Anderson Janotti, David D. Awschalom, Chris G. Van de Walle
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- 14 October 2013
- Published by Springer Nature in MRS Bulletin
Quantum computing with defects
by Luke Gordon, Justin R. Weber, Joel B. Varley, Anderson Janotti, David D. Awschalom, Chris G. Van de Walle
Cited by 78
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Cited by 35
- 1 September 2013
- Published by Elsevier in Microelectronic Engineering
Defects at Ge/oxide and III–V/oxide interfaces
by C.G. Van de Walle, M. Choi, J.R. Weber, J.L. Lyons, A. Janotti
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- 1 September 2013
- Published by Elsevier in Microelectronic Engineering
Defects at Ge/oxide and III–V/oxide interfaces
by C.G. Van de Walle, M. Choi, J.R. Weber, J.L. Lyons, A. Janotti
Cited by 35
Open Access
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Cited by 70
- 14 January 2013
- Published by American Physical Society (APS) in Physical Review B
Dangling bonds and vacancies in germanium
by J. R. Weber, A. Janotti, C. G. Van de Walle
The quest for metal-oxide-semiconductor field-effect transistors (MOSFETs) with higher carrier mobility has triggered great interest in germanium-based MOSFETs. Still, the performance of germanium-based devices lags significantly behind that of their silicon counterparts, possibly due to the presence of defects such as dangling bonds (DBs) and vacancies. Using screened hybrid functional calculations we investigate the role of DBs and vacancies in germanium. We find that the DB defect in germanium has no levels in the band gap; it acts as a negatively charged acceptor with the (0/ $-$ 1) transition level below the valence-band maximum (VBM). This explains the absence of electron-spin-resonance observations of DBs in germanium. The vacancy in germanium has a much lower formation energy than the vacancy in silicon and is stable in a number of charge states, depending on the position of the Fermi level. We find the (0/ $-$ 1) and ( $-$ 1/ $-$ 2) transition levels at 0.16 and 0.38 eV above the VBM; the spacing of these levels is explained based on the strength of intraorbital repulsion. We compare these results with calculations for silicon, as well as with available experimental data.
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- 14 January 2013
- Published by American Physical Society (APS) in Physical Review B
Open Access
Dangling bonds and vacancies in germanium
by J. R. Weber, A. Janotti, C. G. Van de Walle
The quest for metal-oxide-semiconductor field-effect transistors (MOSFETs) with higher carrier mobility has triggered great interest in germanium-based MOSFETs. Still, the performance of germanium-based devices lags significantly behind that of their silicon counterparts, possibly due to the presence of defects such as dangling bonds (DBs) and vacancies. Using screened hybrid functional calculations we investigate the role of DBs and vacancies in germanium. We find that the DB defect in germanium has no levels in the band gap; it acts as a negatively charged acceptor with the (0/ $-$ 1) transition level below the valence-band maximum (VBM). This explains the absence of electron-spin-resonance observations of DBs in germanium. The vacancy in germanium has a much lower formation energy than the vacancy in silicon and is stable in a number of charge states, depending on the position of the Fermi level. We find the (0/ $-$ 1) and ( $-$ 1/ $-$ 2) transition levels at 0.16 and 0.38 eV above the VBM; the spacing of these levels is explained based on the strength of intraorbital repulsion. We compare these results with calculations for silicon, as well as with available experimental data.
Cited by 70
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Cited by 362
- 1 August 2011
- Published by IOP Publishing in New Journal of Physics
Experimental electronic structure of In₂O₃and Ga₂O₃
by Christoph Janowitz, Valentina Scherer, Mansour Mohamed, Alica Krapf, Helmut Dwelk, Recardo Manzke, Zbigniew Galazka, Reinhard Uecker, Klaus Irmscher, Roberto Fornari, et al.
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- 1 August 2011
- Published by IOP Publishing in New Journal of Physics
Top Cited Papers
Open Access
Experimental electronic structure of In₂O₃and Ga₂O₃
by Christoph Janowitz, Valentina Scherer, Mansour Mohamed, Alica Krapf, Helmut Dwelk, Recardo Manzke, Zbigniew Galazka, Reinhard Uecker, Klaus Irmscher, Roberto Fornari, et al.
Cited by 362
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Cited by 94
- 15 May 2011
- Published by AIP Publishing in Journal of Applied Physics
Defects in SiC for quantum computing
by J. R. Weber, W. F. Koehl, J. B. Varley, A. Janotti, B. B. Buckley, C. G. Van de Walle, D. D. Awschalom
The successful implementation of the nitrogen-vacancy (NV) center in diamond as a qubit has spawned a great deal of interest in this defect. In principle, similar defects suitable for quantum computing should exist in other material systems; however, very little work has been done on identifying NV-like centers in other materials. We discuss the key properties of the NV center in diamond in the context of uncovering similar defects in other materials, with the specific example of SiC. Using first-principles calculations, we compare the properties of the NV center in diamond to the analogous defect in 4H-SiC. We also compare the properties of the bare vacancies. We calculate defect formation energies and charge-state transition levels to determine which defects are likely to form. Then, by analyzing the defect-induced electronic states, we determine whether stable defects in 4H-SiC may have properties similar to those of the NV center in diamond.
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- 15 May 2011
- Published by AIP Publishing in Journal of Applied Physics
Defects in SiC for quantum computing
by J. R. Weber, W. F. Koehl, J. B. Varley, A. Janotti, B. B. Buckley, C. G. Van de Walle, D. D. Awschalom
The successful implementation of the nitrogen-vacancy (NV) center in diamond as a qubit has spawned a great deal of interest in this defect. In principle, similar defects suitable for quantum computing should exist in other material systems; however, very little work has been done on identifying NV-like centers in other materials. We discuss the key properties of the NV center in diamond in the context of uncovering similar defects in other materials, with the specific example of SiC. Using first-principles calculations, we compare the properties of the NV center in diamond to the analogous defect in 4H-SiC. We also compare the properties of the bare vacancies. We calculate defect formation energies and charge-state transition levels to determine which defects are likely to form. Then, by analyzing the defect-induced electronic states, we determine whether stable defects in 4H-SiC may have properties similar to those of the NV center in diamond.
Cited by 94
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Cited by 179
- 1 February 2011
- Published by AIP Publishing in Journal of Applied Physics
Native defects in Al2O3 and their impact on III-V/Al2O3 metal-oxide-semiconductor-based devices
by J. R. Weber, A. Janotti, C. G. Van de Walle
${Al}_{2} O_{3}$ is a promising material for use as a dielectric in metal-oxide-semiconductor devices based on III-V compound semiconductors. However, the presence of deep levels and fixed charge in the ${Al}_{2} O_{3}$ layer is still a concern, with native defects being a possible cause of traps, leakage, and fixed charge. We report hybrid density functional calculations for vacancies, self-interstitials, and antisites in ${Al}_{2} O_{3}$ . The energetic positions of defect levels are discussed in terms of the calculated band alignment at the interface between the oxide and relevant III-V materials. We find that oxygen vacancies are the defects most likely to introduce gap levels that may induce border traps or leakage current in a gate stack. In addition, both self-interstitials and aluminum vacancies introduce fixed charge that leads to increased carrier scattering in the channel and shifts the threshold voltage of the device.
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- 1 February 2011
- Published by AIP Publishing in Journal of Applied Physics
Native defects in Al2O3 and their impact on III-V/Al2O3 metal-oxide-semiconductor-based devices
by J. R. Weber, A. Janotti, C. G. Van de Walle
${Al}_{2} O_{3}$ is a promising material for use as a dielectric in metal-oxide-semiconductor devices based on III-V compound semiconductors. However, the presence of deep levels and fixed charge in the ${Al}_{2} O_{3}$ layer is still a concern, with native defects being a possible cause of traps, leakage, and fixed charge. We report hybrid density functional calculations for vacancies, self-interstitials, and antisites in ${Al}_{2} O_{3}$ . The energetic positions of defect levels are discussed in terms of the calculated band alignment at the interface between the oxide and relevant III-V materials. We find that oxygen vacancies are the defects most likely to introduce gap levels that may induce border traps or leakage current in a gate stack. In addition, both self-interstitials and aluminum vacancies introduce fixed charge that leads to increased carrier scattering in the channel and shifts the threshold voltage of the device.
Cited by 179
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Cited by 193
- 22 November 2010
- Published by AIP Publishing in Applied Physics Letters
The electronic structure of β-Ga2O3
by M. Mohamed, C. Janowitz, I. Unger, R. Manzke, Z. Galazka, R. Uecker, R. Fornari, J. R. Weber, J. B. Varley, C. G. Van de Walle
$β {-Ga}_{2} O_{3}$ has the widest energy gap of the transparent conducting oxides. The interest in its electronic properties has recently increased because of its applications in various optoelectronic devices, semiconductor lasers, and ultrasensitive gas detecting systems. In contrast, information on the electronic structure of $β {-Ga}_{2} O_{3}$ is very scarce. Here, we present the experimental valence-band structure of $β {-Ga}_{2} O_{3}$ single crystals determined by high-resolution angle-resolved photoelectron spectroscopy utilizing synchrotron radiation. We find good matching of the experimental band structure with the advanced density functional theory calculations employing hybrid functionals and projector augmented wave potentials.
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- 22 November 2010
- Published by AIP Publishing in Applied Physics Letters
The electronic structure of β-Ga2O3
by M. Mohamed, C. Janowitz, I. Unger, R. Manzke, Z. Galazka, R. Uecker, R. Fornari, J. R. Weber, J. B. Varley, C. G. Van de Walle
$β {-Ga}_{2} O_{3}$ has the widest energy gap of the transparent conducting oxides. The interest in its electronic properties has recently increased because of its applications in various optoelectronic devices, semiconductor lasers, and ultrasensitive gas detecting systems. In contrast, information on the electronic structure of $β {-Ga}_{2} O_{3}$ is very scarce. Here, we present the experimental valence-band structure of $β {-Ga}_{2} O_{3}$ single crystals determined by high-resolution angle-resolved photoelectron spectroscopy utilizing synchrotron radiation. We find good matching of the experimental band structure with the advanced density functional theory calculations employing hybrid functionals and projector augmented wave potentials.
Cited by 193
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Cited by 57
- 8 November 2010
- Published by AIP Publishing in Applied Physics Letters
Intrinsic and extrinsic causes of electron accumulation layers on InAs surfaces
by J. R. Weber, A. Janotti, C. G. Van de Walle
Using first-principles calculations we investigate the origins of electron accumulation on InAs surfaces. Among the possible intrinsic causes (i.e., involving only In and/or As), In adatoms are the only native defects that can induce a surface electron accumulation layer. As an extrinsic mechanism, we find that adsorption of hydrogen on the surface also leads to charge accumulation. Hydrogen is an ubiquitous impurity, present in all growth and processing environments and therefore likely to be present on InAs surfaces. Both indium and hydrogen adatoms create donor states above the InAs conduction-band minimum and can explain the observed electron accumulation.
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- 8 November 2010
- Published by AIP Publishing in Applied Physics Letters
Intrinsic and extrinsic causes of electron accumulation layers on InAs surfaces
by J. R. Weber, A. Janotti, C. G. Van de Walle
Using first-principles calculations we investigate the origins of electron accumulation on InAs surfaces. Among the possible intrinsic causes (i.e., involving only In and/or As), In adatoms are the only native defects that can induce a surface electron accumulation layer. As an extrinsic mechanism, we find that adsorption of hydrogen on the surface also leads to charge accumulation. Hydrogen is an ubiquitous impurity, present in all growth and processing environments and therefore likely to be present on InAs surfaces. Both indium and hydrogen adatoms create donor states above the InAs conduction-band minimum and can explain the observed electron accumulation.
Cited by 57
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Cited by 1114
- 4 October 2010
- Published by AIP Publishing in Applied Physics Letters
Oxygen vacancies and donor impurities in β-Ga2O3
by J. B. Varley, J. R. Weber, A. Janotti, C. G. Van de Walle
Using hybrid functionals we have investigated the role of oxygen vacancies and various impurities in the electrical and optical properties of the transparent conducting oxide $β {-Ga}_{2} O_{3}$ . We find that oxygen vacancies are deep donors, and thus cannot explain the unintentional $n$ -type conductivity. Instead, we attribute the conductivity to common background impurities such as silicon and hydrogen. Monatomic hydrogen has low formation energies and acts as a shallow donor in both interstitial and substitutional configurations. We also explore other dopants, where substitutional forms of Si, Ge, Sn, F, and Cl are shown to behave as shallow donors.
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- 4 October 2010
- Published by AIP Publishing in Applied Physics Letters
Top Cited Papers
Oxygen vacancies and donor impurities in β-Ga2O3
by J. B. Varley, J. R. Weber, A. Janotti, C. G. Van de Walle
Using hybrid functionals we have investigated the role of oxygen vacancies and various impurities in the electrical and optical properties of the transparent conducting oxide $β {-Ga}_{2} O_{3}$ . We find that oxygen vacancies are deep donors, and thus cannot explain the unintentional $n$ -type conductivity. Instead, we attribute the conductivity to common background impurities such as silicon and hydrogen. Monatomic hydrogen has low formation energies and acts as a shallow donor in both interstitial and substitutional configurations. We also explore other dopants, where substitutional forms of Si, Ge, Sn, F, and Cl are shown to behave as shallow donors.
Cited by 1114

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