Research Interests

• Study of the structural, electronic, optical and optoelectronic properties of semiconductors and nanostructures, emphasizing the relationships among defects, electronic structure, and device performance
• Surface and interface effects
• Alloy effects

The main tools applied to these problems are theory and computation using primarily ab initio electronic structure, molecular dynamics, and kinetic Monte Carlo, but experiments are also employed including optical and X-ray spectroscopy and transmission electron microscopy. A common theme is the study of “real” materials to enable effective materials design. Recent topics include materials for:

• Superconducting, ion-trap, and silicon-quantum-dot qubits
• High-energy radiation detectors
• Lithium-ion batteries
• Thin-film solar cells
• Advanced nuclear fuels
• Magnets
• Wide band gap and ultra wide band gap electronics
• Catalysts

https://qsg.llnl.gov

Career Path

• 3 years KLA Corporation
• 14 years in the Quantum Simulations Group, LLNL

Current Projects

Current projects span various applications:

• Surface, interface, and defect engineering and design of materials for superconducting, semiconducting, and ion trap qubits
• Semiconductor and amorphous materials for high-energy radiation detection
• Interface chemistry in lithium ion batteries
• Buffer layer materials for high-performance thin-film photovoltaic devices
• Glass doping for tunable optical filters in high-fluence applications
• “Integrated Physics-Based Noise Modeling of Qubit Devices” (LDRD) — Lead a team of computational materials scientists, quantum dynamics experts, and device simulation experts to build and exercise an integrated multi-scale modeling tool to address the materials origins of noise in quantum bits and ultimately enable higher fidelity quantum computers.
• “Anomalous Heating in Ion Trap Qubits” — Lead a team of computational materials scientists and quantum device physicists to explore the mechanisms of decoherence in ion trap qubits and devise mitigation strategies.
• “Metastability and Long-term Degradation in CIGS Devices” (EERE) — Experimental and computational studies of CIGS solar cell degradation pathways through accelerated testing coupled to multi-scale, multi-physics modeling.
• “Critical Materials Institute: Materials Design Simulators” (DOE Energy Hub) — Contributor on multi-dimensional constrained phase-space search and optimization of thermodynamic data to help discover novel material compositions for reduced-rare earth permanent magnets; optimization of doping of wide band gap materials, including gallium oxide, for power applications. Development of LLNL Materials Design Simulator (MDS).

Past Projects

• “Low Noise Qubits” (LDRD) — First principles modeling of atomic structures and associated magnetic properties at surfaces and interfaces to discover possible atomic sources of decoherence in superconducting qubits, enabling process strategies to fabricate longer coherence time devices. 
• “Rational Design of Wide Band Gap Buffer Layers for High-Efficiency Thin-Film Photovoltaics” (DOE/EERE) — Lead a team of computational and experimental materials scientists in collaboration with an industry partner to help develop next generation materials for high-efficiency thin-film solar cells. Combines theoretical defect properties in semiconductors, device simulation, atomic-scale characterization with electron microscopy, and world-class device fabrication/materials synthesis.
• “Discontinuous methods for accurate, massively parallel quantum molecular dynamics: Lithium ion interface dynamics from first principles” (DOE/BES + DOE/ASCR SciDAC) — Aim to use large-scale first principles molecular dynamics to study chemistry at interfaces in lithium-ion batteries to enable rational design of safer, longer-life, higher-capacity batteries using detailed knowledge of the failure mechanisms and limiting processes. The project also involves development of code implementing a new method to enable fast, very large-scale first principles molecular dynamics.
• “Materials Modeling for High-Performance Radiation Detectors” (NNSA/NA-22) — Lead a team of computational materials scientists that interface with experimental collaborators to discover and design optimal materials for high-performance room-temperature high-energy radiation detectors. Focus on electronic and mass transport in materials and defect properties.
• “Predictive Modeling of Electronic Transport in Semiconductors for Radiation Detectors” (LDRD) — Development of first principles methods to predict transport properties in semiconductors containing defects, with the target application of optimizing materials for gamma radiation detection 
• “Scientific Basis for Ultra-high Burn-up Nuclear Fuels” (LDRD) — Contributed thermodynamic and kinetic modeling of phase evolution in complex metal alloy mixtures relevant to optimizing materials for a novel ultra-high burn-up inert metal matrix nuclear fuel concept.
• “Optimization and Assessment of Semiconductor Radiation Detector Materials Utilizing First-Principles Simulations” (NNSA/NA-22) — Application of first principles modeling of defect electronic, thermodynamic, and kinetic properties in semiconductors used in room-temperature gamma radiation detectors, to enable optimization of synthesis properties. Collaboration with crystal growth teams. 

Ph.D., Materials Science & Engineering, Stanford University (Hertz Fellow), 2004

M.S., Electrical Engineering, Stanford University, 2002

B.S.E., Chemical Engineering, Princeton University, 1999 (minors: Applied Mathematics, Materials Science)

1. C.J.K. Richardson, V. Lordi, S. Misra, and J. Shabani, “Materials Science for Quantum Information Science and Technology,” MRS Bulletin 45(6), 485 (2020).
2. V. Lordi, “Delving into dynamic effects,” Nature Chemistry 12, 225 (2020).
3. M. Nardone, Y. Patikirige, K.E. Kweon, C. Walkons, T. Magorian Friedlmeier, J.B. Varley, V. Lordi, and S. Bansal, “Quantifying Large Lattice Relaxations in Photovoltaic Devices,” Physical Review Applied 13, 024025 (2020).
4. C. Noel, M. Berlin-Udi, C. Matthiesen, J. Yu, Y. Zhou, V. Lordi, and H. Häffner, “Electric-field noise from thermally activated fluctuators in a surface ion trap,” Physical Review A 99, 063427 (2019).
5. K.G. Ray, B.M. Rubenstein, W. Gu, and V. Lordi, “van der Waals-corrected density functional study of electric field noise heating in ion traps caused by electrode surface adsorbates,” New Journal of Physics 21, 053043 (2019). 
6. X. He, J.B. Varley, P. Ercius, T. Erikson, J. Bailey, G. Zapalac, T. Nagle, D. Poplavskyy, N. Mackie, A. Bayman, V. Lordi, and A. Rockett, “The role of oxygen doping on elemental intermixing at the PVD-CdS/Cu(InGa)Se2heterojunction,” Progress in Photovoltaics: Research and Applications 27, 255-263 (2019).
7. Y. Wang, P.T. Dickens, J.B. Varley, X. Ni, E. Lotubai, S. Sprawls, F. Liu, V. Lordi, S. Krishnamoorthy, S. Blair, K.G. Lynn, M. Scarpulla, and B. Sensale-Rodriguez, “Incident wavelength and polarization dependence of spectral shifts in beta-Ga2O3 UV photoluminescence,” Scientific Reports 8, 18075 (2018).
8. A. Kumar, H. Barda, M.W. Finnis, V. Lordi, E. Rabkin, and D.J. Srolovitz, “Anomalous Diffusion at Metal-Ceramic Interfaces,” Nature Communications 9, 5251 (2018).
9. X.-Y. Liu, B. Arey, I. Arslan, J. Hackley, V. Lordi, C.J.K. Richardson, “Perfect strain relaxation in metamorphic epitaxial aluminum on silicon through primary and secondary interface misfit dislocation arrays,” ACS Nano 12, 6843 (2018).
10. C.-E. Kim, K.G. Ray, D.F. Bahr, and V. Lordi, “Electronic structure and surface properties of MgB2(0001) upon oxygen adsorption,” Physical Review B 97, 195416 (2018).
11. K.E. Kweon and V. Lordi, “First principles study of the structural, electronic, and optical properties of Sn2+-doped ZnO-P2O5,” Journal of Non-Crystalline Solids 492, 108 (2018).
12. A. Landa, P. Söderlind, D. Parker, D. Åberg, V. Lordi, A. Perron, P.E.A. Turchi, R.K. Chouhan, D. Paudyal, and T.A. Lograsso, “Thermodynamics of the SmCo5 compound doped with Fe and Ni: an ab initio study,” Journal of Alloys and Compounds 765, 659 (2018).
13. J.B. Varley, V. Lordi, T. Ogitsu, A. Deangelis, K. Horsley and N. Gaillard, “Hydrogen-induced Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles,” Journal of Applied Physics  123, 161408 (2018).
14. H. Bhatia, A.G. Gyulassy, V. Lordi, J.E. Pask, V. Pascucci, and P.-T. Bremer, “TopoMS: Comprehensive Topological Exploration for Molecular and Condensed-Matter Systems,” Journal of Computational Chemistry 39, 925 (2018).
15. J. Varley, A. Samanta, and V. Lordi, “Descriptor-Based Approach for the Prediction of Cation Vacancy Formation Energies and Transition Levels,” The Journal of Physical Chemistry Letters 8, 5059 (2017).
16. T.A. Pham, K.E. Kweon, A. Samanta, V. Lordi, and J. Pask, “Solvation and Dynamics of Sodium and Potassium in Ethylene Carbonate from Ab Initio Molecular Dynamics Simulations,” The Journal of Physical Chemistry Part C 121, 21913 (2017).
17. J.B. Varley, V. Lordi, X. He, and A. Rockett, “Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics,” Physical Review Materials 1, 025403 (2017).
18. M.T. Ong, H. Bhatia, A.G. Gyulassy, E.W. Draeger, V. Pascucci, P.-T. Bremer, V. Lordi, and J.E. Pask, “Complex Ion Dynamics in Carbonate Lithium-Ion Battery Electrolytes,” Journal of Physical Chemistry C 121, 6589 (2017).
19. N. Adelstein, D. Lee, J.L. DuBois, and V. Lordi, “Magnetic stability of oxygen defects on the SiO2 surface,” AIP Advances 7, 025110 (2017).
20. J.B. Varley, X. He, A. Rockett, and V. Lordi, “Stability of Cd1–xZnxOyS1–y Quaternary Alloys Assessed with First-Principles Calculations,” ACS Applied Materials & Interfaces 9, 5673 (2017).
21. X. He, T. Paulauskas, P. Ercius, J. Varley, J. Bailey, G. Zapalac, D. Poplavskyy, N. Mackie, A. Bayman, R. Klie, V. Lordi, A. Rockett, “Cd doping at PVD-CdS/CuInGaSe2 heterojunctions,” Solar Energy Materials and Solar Cells 164, 128 (2017).
22. X.Q. He, J.B. Varley, P. Ercius, T. Erikson, J. Bailey, G. Zapalac, D. Poplavskyy, N. Mackie, A. Bayman, V. Lordi, and A. Rockett, “Intermixing and Formation of Cu-Rich Secondary Phases at Sputtered CdS/CuInGaSe2 Heterojunctions,” IEEE J. of Photovoltaics 6, 1308 (2016).
23. K.E. Kweon, D. Åberg, and V. Lordi, “First-principles study of atomic and electronic structures of 60° perfect and 30°/90° partial glide dislocations in CdTe,” Physical Review B 93, 174109 (2016).
24. J.B. Varley, V. Lordi, X. He, and A. Rockett, “First principles calculations of point defect diffusion in CdS buffer layers: Implications for Cu(In,Ga)(Se,S)2 and Cu2ZnSn(Se,S)4-based thin-film photovoltaics,”Journal of Applied Physics 119, 025703 (2016).
25. N. Adelstein, C.S. Olson, and V. Lordi, “Hole traps in sodium silicate: first-principles calculations of the mobility edge,” Journal of Non-Crystalline Solids 430, 9 (2015).
26. J.B. Varley, A.M. Conway, L.F. Voss, E. Swanberg, R.T. Graff, R.J. Nikolic, S.A. Payne, V. Lordi, and A.J. Nelson, “Effect of chlorination on the TlBr band gap for improved room temperature radiation detectors,” Physica Status Solidi B 252, 1266 (2015). [Back Cover article]
27. M.T. Ong, O. Verners, E.W. Draeger, A.C.T. van Duin, V. Lordi, and J. Pask, “Lithium Ion Solvation and Diffusion in Bulk Organic Electrolytes from First Principles and Classical Reactive Molecular Dynamics,” Journal of Physical Chemistry B 119, 1535 (2014).
28. P. Soderlind, P.E.A. Turchi, A. Landa, and V. Lordi, “Ground-state properties of rare-earth metals: An evaluation of density-functional theory,” Journal of Physics: Condensed Matter 26, 416001 (2014).
29. J.B. Varley and V. Lordi, “Intermixing at the absorber-buffer layer interface in thin-film solar cells: The electronic effects of point defects in Cu(In,Ga)(Se,S)2 and Cu2ZnSn(Se,S)4 devices,” Journal of Applied Physics 116, 063505 (2014).
30. X.Q. He, G. Brown, K. Demirkan, N. Mackie, V. Lordi, A. Rockett, “Microstructural and Chemical Investigation of PVD-CdS/PVD-CuIn1–xGaxSe2 Heterojunctions: A Transmission Electron Microscopy Study,” IEEE J. of Photovoltaics 4, 1625 (2014).
31. D. Lee, J.L. Dubois, and V. Lordi, “Identification of the Local Sources of Paramagnetic Noise in Superconducting Qubit Devices Fabricated on alpha-Al2O3 Substrates Using Density-Functional Calculations,” Physical Review Letters (Editor’s Selection) 112, 017001 (2014).
32. P. Söderlind, B. Sadigh, V. Lordi, A. Landa and P.E.A. Turchi, “Electron correlation and relativity of the 5f electrons in the U–Zr alloy system,” Journal of Nuclear Materials 444, 356 (2014).
33. J.B. Varley and V. Lordi, “Electrical properties of point defects in CdS and ZnS,” Applied Physics Letters 103, 102103 (2013).
34. G. Wang, Y. Ling, X. Lu, F. Qian, Y. Tong, J.Z. Zhang, V. Lordi, C.R. Leão, and Y. Li, “Computational and Photoelectrochemical Study of Hydrogenated Bismuth Vanadate,” Journal of Physical Chemistry C 117, 10957 (2013).
35. D. Åberg, P. Erhart, and V. Lordi, “Contributions of point defects, chemical disorder, and thermal vibrations to electronic properties of Cd1−xZnxTe alloys,” Physical Review B 88, 045201 (2013).
36. V. Lordi, “Point Defects in Cd(Zn)Te and TlBr: Theory,” Journal of Crystal Growth (invited special issue) 379, 84 (2013).
37. C. Rocha-Leão and V. Lordi, “Ionic current and polarization effect in TlBr,” Physical Review B 87, 081202(R) (2013).
38. C. Rocha-Leão and V. Lordi, “Simultaneous Control of Ionic and Electronic Conductivity in Materials: Thallium Bromide Case Study,” Physical Review Letters 108, 246604 (2012).
39. C. Rocha-Leão and V. Lordi, “Ab initio guided optimization of GaTe for radiation detection applications,” Physical Review B 84, 165206 (2011).
40. V. Lordi, P. Erhart, and D. Åberg, “Charge carrier scattering by defects in semiconductors,” Physical Review B 81, 235204 (2010).
41. P. Erhart, D. Åberg, B.W. Sturm, K.-J. Wu, and V. Lordi, “Theory-Guided Growth of Aluminum Antimonide Single Crystals with Optimal Properties for Radiation Detection,” Applied Physics Letters 97, 142104 (2010).
42. P. Erhart, D. Åberg, and V. Lordi, “Extrinsic point defects in aluminum antimonide,” Physical Review B 81, 195216 (2010).
43. N.P. Zaitseva, J. Newby, S. Hamel, L. Carman, M. Faust, V. Lordi, N.J. Cherepy, W. Stoeffl, S.A. Payne, “Neutron detection with single crystal organic scintillators,” Proc. SPIE 7449, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XI, 744911 (2009).
44. D. Åberg, P. Erhart, A.J. Williamson, and V. Lordi, “Intrinsic point defects in aluminum antimonide,” Physical Review B 77(16), 165206 (2008).
45. T.T.M. Vo, A.J. Williamson, V. Lordi, G. Galli, “Atomistic design of thermoelectric properties of silicon nanowires,” Nano Letters 8(4), 1111 (2008).
46. V. Lordi, H.B. Yuen, S.R. Bank, M.A. Wistey, S. Friedrich, and J.S. Harris, “Nearest neighbor distributions in GaInNAs(Sb) upon annealing,” Physical Review B 71(12), 125309 (2005).
47. V. Lordi, H. Yuen, S. Bank, and J.S. Harris, “Quantum confined Stark effect of GaInNAs(Sb) quantum wells at 1300-1600 nm,” Applied Physics Letters 85(6), 902 (2004).
48. V. Lordi, V. Gambin, S. Friedrich, T. Funk, T. Takizawa, K. Uno, and J.S. Harris, “Nearest-neighbor configuration in (GaIn)(NAs) probed by x-ray absorption spectroscopy,” Physical Review Letters 90(14), 145505 (2003).
49. V. Lordi, N. Yao, and J. Wei, “Method for Supporting Platinum on Single-Walled Carbon Nanotube for a Selective Hydrogenation Catalyst,” Chemistry of Materials 13(3), 733 (2001).