Research Interests

Timothy Boykin's research centers on the physics of quantum wells, superlattices, resonant-tunneling diodes, and other quantum-confined heterostructures. Most of his work has involved modeling these structures with empirical tight-binding techniques in order to include bandstructure effects. Highlights of his research include the first numerically-stable, realistic bandstructure empirical tight-binding calculation for a resonant-tunneling diode including space-charge regions (1991), investigations of nonparabolicity effects on quantum-confined heterostructures (1993-95), the generalized eigenproblem method for obtaining surface and interface states (1996), incompleteness in tight-binding models (1995), analytic effective mass expressions for and investigations of the capabilities of many commonly employed tight-binding models (1997-99), representing electromagnetic interactions in tight-binding (1999-2002), and modeling of strain in heterstructures (2002).

Degrees

• B.S.E.E., Rice University (summa cum laude), Electrical Engineering, 1987.
• M.S., Stanford University, Electrical Engineering, 1988.
• Ph.D., Stanford University, Electrical Engineering, 1992.

Recent Publications

S. Ahmed, N. Kharche, R. Rahman, M. Usman, S. Lee, H. Ryu, H. Bae, S. clark, B. Haley, M. Naumov, M. Luisier, F. Saied, M. Korkusinski, R. Kennel, M. McLennan, T. Boykin, and G. Klimeck, “Multimillion Atom Simulations with NEMO 3-D and Deployment on nanoHUB.org,” in Encyclopedia of Complexity and System Science, ed. R. A. Meyers (Springer, New York, tentatively 2009). Published Europe April 2009; USA May-June 2009.

Neerav Kharche, Seongmin Kim, Timothy B. Boykin, and Gerhard Klimeck, “Valley
degeneracies in (111) silicon quantum wells,” Applied Physics Letters 94, 042201 (2009).

Timothy B. Boykin, Neerav Kharche, and Gerhard Klimeck, “Non-primitive rectangular
supercells for tight-binding electronic structure calculations,” Physica E 41, 490 (2009).

Timothy B. Boykin, Mathieu Luisier, and Gerhard Klimeck, “Multi-band transmission
calculations for nanowires using an optimized renormalization method,” Physical Review B 77, 165318 (2008).

Timothy B. Boykin, Neerav Kharche, and Gerhard Klimeck, “Valley splitting in finite barrier quantum wells,” Physical Review B 77, 245320 (2008).

Neerav Kharche, Mathieu Luisier, Timothy B. Boykin, and Gerhrd Klimeck, “Electronic
structure and transmission characteristics of SiGe Nanowires,” Journal of Computational
Electronics 7, 350 (2008).

Timothy B. Boykin, Neerav Kharche, Mathieu Luisier, Gerhard Klimeck, “Zone Unfolding and Approximate Bandstructure Calculations in Tight-Binding,” American Physical Society, March Meeting 2008, New Orleans, LA.

Timothy B. Boykin, Neerav Kharche, and Gerhard Klimeck, “Brillouin zone unfolding of perfect supercells having non-equivalent primitive cells illustrated with a Si/Ge tight-binding parameterization,” Physical Review B 76, 035310 (2007).

Gerhard Klimeck, Shaikh Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, Marta Prada, and Timothy B. Boykin, “Atomistic simulation of realistically sized nanodevices using NEMO 3-D: II-Applications,” IEEE Transactions on Electron Devices 54, 2090 (2007).

Gerhard Klimeck, Shaikh Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, Marta Prada, and Timothy B. Boykin, “Atomistic simulation of realistically sized nanodevices using NEMO 3-D: I-Models and Benchmarks,” IEEE Transactions on Electron Devices 54,
2079 (2007).

Timothy B. Boykin, Neerav Kharche, Gerhard Klimeck, and Marek Korkusinski, "Approximate bandstructures of semiconductor alloys from tight-binding supercell calculations," Journal of Physics: Condensed Matter 19, 036203 (2007).

Timothy B. Boykin, Mathieu Luisier, Andreas Schenk, Neerav Kharche, and Gerhard Klimeck, "The electronic structure and transmission characteristics of disordered AlGaAs nanowires," IEEE Transactions on Nanotechnology 6, 43 (2007).

Neerav Kharche, Marta Prada, Timothy B. Boykin, and Gerhard Klimeck, "Valley splitting in strained Si quantum wells with 2degree miscuts, step disorder, and alloy disorder," Applied Physics Letters 90, 092109 (2007).

Timothy B. Boykin, Neerav Kharche, and Gerhard Klimeck, "Allowed wavevectors under the application of incommensurate periodic boundary conditions," European Journal of Physics 27, 5 (2006).

A. S. Martins, Timothy B. Boykin, Gerhard Klimeck, and Belita Koiller, "Conduction-band tight-binding description for Si applied to P donors," Physical Review B 72, 193204 (2005).

Timothy B. Boykin and Gerhard Klimeck, "The discretized Schrodinger equation for the finite square well and its relationship to solid-state physics," European Journal of Physics 26, 865 (2005).

Dennis Hite, Timothy B. Boykin, Nagendra Singh, and Dashen Shen, "A simple Fermi-Dirac Integrating Circuit," American Journal of Physics (2005).

Timothy B. Boykin and Gerhard Klimeck, "Practical Application of Zone-Folding Concepts in Tight-Binding," Physical Review B 71, 115215 (2005).

Timothy B. Boykin and Gerhard Klimeck, "The discretized Schrödinger equation and simple models for semiconductor quantum wells," European Jouornal of Physics 25, 503 (2004).

Timothy B. Boykin, Gerhard Klimeck, M. A. Eriksson, Mark Friesen, S. N. Coppersmith, Paul von Allmen, Fabiano Oyafuso, and Seungwon Lee, "Valley splitting in low-density quantum-confined heterostructures studied using tight-binding models," Phys. Rev. B 70, 165325 (2004).

Timothy B. Boykin, Gerhard Klimeck, and Fabiano Oyafuso, "Valence band effective mass expressions in the sp3d5s* empirical tight-binding model applied to a Si and Ge parameterization," Physical Review B 69, 115201 (2004).

Timothy B. Boykin, Gerhard Klimeck, Mark Eriksson, Mark Friesen, S. N. Coppersmith, Paul von Allmen, Fabiano Oyafuso, and Seungwon Lee, "Valley splitting in strained Si quantum wells," Applied Physics Letters 84, 115 (2004).

Fabiano Oyafuso, Gerhard Klimeck, Paul von Allmen, Timothy B. Boykin, and R. Chris Bowen, "Strain effects in large-scale atomistic quantum dot simulations," Physica Status Solidi b 239, 71 (2003).

Fabiano Oyafuso, Gerhard Klimeck, R. Chris Bowen, Timothy B. Boykin, and Paul von Allmen, "Disorder-induced broadening in multimillion atom alloyed quantum dot systems," Physica Status Solidi c 0004, 1149 (2003).

Timothy B. Boykin, "Derivatives of the Dirac delta function by explicit construction of sequences," American Journal of Physics 71, 462 (2003).

Gerhard Klimeck, Fabiano Oyafuso, Timothy B. Boykin, R. Chris Bowen, and, Paul von Allmen, "Development of a Nanoelectronic 3-D (NEMO 3-D) Simulator for Multimillion Atom Simulations and Its Application to Alloyed Quantum Dots," Journal of Computer Modeling in Engineering and Science, 3, 601 (2002), invited.

Gerhard Klimeck, Fabiano Oyafuso, R. Chris Bowen, Timothy B. Boykin, Thomas A. Cwik, Edith Huang, and Edward Vinyard, "3-D Atomistic Nanoelectronic Modeling on High Performance Clusters: Multimillion Atom Simulations," Superlattices and Microstructures, 31, 171 (2002).

Fabiano Oyafuso, Gerhard Klimeck, R. Chris Bowen, and Timothy B. Boykin, "Atomistic Electronic Structure Calculations of Unstrained Alloyed Systems Consisting of a Million Atoms," Journal of Computational Electronics, 1, 317 (2002).

"Diagonal parameter shifts due to nearest-neighbor displacements in empirical tight-binding theory," Timothy B. Boykin, Gerhard Klimeck, R. Chris Bowen, and Fabiano Oyafuso, Physical Review B 66, 125207 (2002).

Timothy B. Boykin, Dennis Hite, and Nagendra Singh, "The two-capacitor problem with radiation," American Journal of Physics 70, 415 (2002).

Timothy B. Boykin and P. Vogl, "Dielectric response of molecules in empirical tight-binding theory," Physical Review B 65 035202 (2002).

Timothy B. Boykin, R. Chris Bowen, and Gerhard Klimeck, "Electromagnetic coupling and gauge invariance in the empirical tight-binding method," Physical Review B 63, 245314 (2001).

Gerhard Klimeck, R. Chris Bowen, and Timothy B. Boykin, "Off zone-center or indirect bandgap-like hole transport in heterostructures," Physical Review B 63, 195310 (2001).

Gerhard Klimeck, R. Chris Bowen, and Timothy B. Boykin, "Strong wavevector dependence of hole transport in heterostructures," Superlattices and Microstructures 29, 187 (2001).

Timothy B. Boykin, "Tight-binding-like expressions for the continuous-space electromagnetic coupling Hamiltonian," American Journal of Physics 69, 793 (2001).

Gerhard Klimeck, R. Chris Bowen, Timothy B. Boykin, and Thomas A. Cwik, "sp3s* tightbinding parameters for transport simulations in compound semiconductors," Superlattices and Microstructures 27, 519 (2000).

Gerhard Klimeck, R. Chris Bowen, Timothy B. Boykin, Carlos Salazar-Lazaro, Thomas A. Cwik, and Adrian Stoica, "Tight-binding models for Si quantum devices and parameter fitting using genetic algorithms," Superlattices and Microstructures 27, 77 (2000).

Timothy B. Boykin, "An alternative view of the continuity equation in quantum mechanics," American Journal of Physics 68, 665 (2000).

Timothy B. Boykin, "Exact representation of exp(iqr) in the empirical tight-binding method and its application to electromagnetic interactions," Physical Review B 60, 15 810 (1999).

Timothy B. Boykin, R. Chris Bowen, Gerhard Klimeck, and Kevin L. Lear, "Resonanttunneling diodes with emitter prewells," Applied Physics Letters 75, 1302 (1999).

J.G. Menchero and Timothy B. Boykin, "Impurity states in semiconductors calculated via tight-binding: a parameter sensitivity study," Physical Review B 59, 8137 (1999).

Timothy B. Boykin, Roger K. Lake, Gerhard Klimeck, and Mukund Swaminathan, "Interface effects in tunneling models with identical real and complex dispersions," Physical Review B 59, 7316 (1999).

Timothy B. Boykin, Lisa J. Gamble, Gerhard Klimeck, and R. Chris Bowen, "Valence-band warping in tight-binding models," Physical Review B 59, 7301 (1999).

Timothy B. Boykin, "A more physical formulation of the self-inductance for spatially distributed circuits," American Journal of Physics 67, 320 (1999).

Timothy B. Boykin, "More complete treatment of spin-orbit effects in tight-binding models," Physical Review B 57, 1620 (1998).

Timothy B. Boykin, "Improved fits of effective masses at à in the spin-orbit, second-nearneighbor sp3s* model: results from analytic expressions," Physical Review B 56, 9613
(1997).

Timothy B. Boykin, Gerhard Klimeck, R. Chris Bowen, and Roger Lake, "Effective mass reproducibility of the nearest-neighbor sp3s* models: analytic results," Physical Review B 56, 4102 (1997).

Timothy B. Boykin and Herman C. Chui, "Simplified treatment of many-body effects in the intersubband absorption of symmetric, uniformly doped quantum wells at zero temperature," Physical Review B 55, 7091 (1997).

Timothy B. Boykin, "Tunneling calculations for systems with singular coupling matrices: results for a simple model," Physical Review B 54, 7670 (1996).

Timothy B. Boykin, "Generalized eigenproblem method for surface and interface states: the complex bands of GaAs and AlAs," Physical Review B 54, 8107 (1996).

Timothy B. Boykin, "Incorporation of incompleteness in the kp perturbation theory," Physical Review B 52, 16 317 (1995).

Timothy B. Boykin and C.D. Johnson, "A generalized solution expression for linear, homogeneous, constant-coefficient difference equations," Journal of the Franklin Institute 332B, 227 (1995).

Timothy B. Boykin, "Approximations for the resonant-tunneling diode current: implications for triple-barrier devices," Journal of Applied Physics 78, 6818 (1995).

Timothy B. Boykin, "Current-voltage calculations for InAs/AlSb resonant-tunneling diodes," Physical Review B 51, 4289 (1995).

Timothy B. Boykin, R.E. Carnahan, and K.P. Martin, "Inadequacy of the one-dimensional approximation for resonant-tunneling diode current-voltage calculations," Physical Review B 51, 2273 (1995).

Timothy B. Boykin, R.E. Carnahan, and K.P. Martin, "Validity of the semiclassical interpretation of resonant magnetotunneling experiments," Physical Review B 50, 15 393 (1994).

Timothy B. Boykin, "Conduction-band states of thin InAs/AlSb quantum wells," Applied Physics Letters 64, 1529 (1994).

Timothy B. Boykin, R.E. Carnahan, and R.J. Higgins, "Quantum well states of InAs/AlSb resonant tunneling diodes," Physical Review B 48, 14 232 (1993).

Timothy B. Boykin, "Resonance features of a two-state model," Physical Review B 47, 12696 (1993).

Timothy B. Boykin, Bardia Pezeshki, and James S. Harris, Jr., "Anti-resonances in the transmission of a simple two-state model," Physical Review B 46, 12 769 (1992).

Timothy B. Boykin, and James S. Harris, Jr., "X-valley tunneling in single AlAs barriers," Journal of Applied Physics 72, 988 (1992). [SU]

B. Pezeshki, S.M. Lord, T.B. Boykin, and J.S. Harris, Jr., "GaAs/AlAs quantum wells for electroabsorption modulators," Applied Physics Letters 60, 2779 (1992).

B. Pezeshki, S.M. Lord, T.B. Boykin, B.L. Shoop, and J.S. Harris, Jr., "AlGaAs/GaAs QW modulator for 6328 Å operation," Electronics Letters 27, 1971 (1991).

Timothy B. Boykin, Jan P.A. van der Wagt, and James S. Harris, Jr., "Tight-binding model for GaAs/AlAs resonant tunneling diodes," Physical Review B 43, 4777 (1991).