Current research interests are motivated by the following forces:
- Is it possible to tailor the electron-phonon interaction in semiconductor structures? If this is possible, it would open the possibility of new devices that would be temperature insensitive. It would also allow us to develop quantum devices that could operate at high temperatures.
- How can quantum confined states in semiconductors be exploited for fan infrared (~10mm) detectors and lasers? These devices would be extremely useful for night vision, thermal imaging and communication through media like fog, plastic fibers, etc.
- How does the silicon-silicon oxide interface used in MOSFET influence transport once device dimensions go below 0.1/mu m? In particular, how important are states localized because of interface disorder?
- How does the initial growth of high lattice mismatched materials on a substrate occur? When does self-assembly of tiny islands occur and how can these islands be exploited for terrabit memories and 0-dimensional optoelectronics?
The following research topics are currently being explored:
- Semiconductor quantum dots produced by strained epitaxy for inter-subband and inter-band devices: We are examining the physics of quantum dots for applications in devices. The project involves the following ingredients:
- Strain tensor calculations using numerical models
- Bandstructure calculations using the 8 band k.p method and tight binding methods
- Optical transistors: both intersubband and interband
- Carrier scattering calculations
- Monte Carlo transport and rate equations for the electron-hole and photon system
- Physics of Si, SiGe and amorphous Si MOSFETS: We are interested in how structural disorder influences the electronic states in devices. We are also interested in how the effect of disorder is manifested in transport. To address this problem, we are developing self-constant solutions to the 3-dimensional MOSFET problem
- High speed semiconductor lasers: We are working in the area of design of high speed lasers based on strained quantum well and quantum dot lasers. Techniques to eliminate carrier thermalization time related limitations are being explored
Some Recent Publications
Our group has published over 200 refereed papers. Some of the recents papers are:
"Channel Effective Mass and Interfacial Effects in Si and SiGe Metal-Oxide-Semiconductor Field Effect Transistor: A ChargeControl Model Study," Y. Zhang and J.Singh, Journal of Applied Physics, 23, 4264 (1998).
"Strain Distribution and Electronic Spectra of InAs/GaAs Self-Assembled Dots: An 8-band Study," H.Jiang and J.Singh, Physical Review, B, 56, 4696 (1998).
"Self-Assembled Semiconductor Structures: Electronic and Optoelectronic Properties," H. Jiang and J.Singh, IEEE Journal of Quantum Electronics, 34, 1188 (1998).
"Charge Control and Mobility Studies for an AlGaN/GaN High Electron Mobility Transistor," Y.Zhang and J.Singh, Journal of Applied Physics, January (1999).
"Use of Kubo Formalism to Study Transport Beyond Born Approximation: Applications to Low Temperature Transport in MOSFETs," Y.Zhang and J.Singh, to appear in Applied Physics Letters, Nov. 11, 1998 issue.
"Carrier Dynamics Studies Through Free-Carrier Absorption: A Monte Carlo Study for Silicon,"H.Jiang, J.M.Hinckley and J.Singh, IEEE Journal of Quantum Electronics, 33, 1779 (1997).
"Design Studies for Distributed Bragg Reflectors for Short-Cavity Edge-Emitting Lasers," R.Jambunathan and J.Singh, IEEE Journal of Quantum Electronics, 33, (1997).
"Electroabsorption and Electrooptic Effect in SiGe-Si Quantum Wells: Realization ofLow-Voltage Optical Modulations," O.Qasaimeh, J.Singh and P.Bhattacharya, IEEE Journal of Quantum Electronics, 33, 1532 (1997).
"Channel Effective Mass and Interfacial Effects in Si and SiGe Metal-Oxide-Semiconductor Field Effect Transistor: A Charge Control Model Study," Y.Zhang and J.Singh, Journal of Applied Physics, 23, 4264 (1998).
"Multispectral InGaAs/GaAs/AlGaAs Laser Arrays by MBE Growth on Patterned Substrates," K.Kamath, P.Bhattacharya and J.Singh, Journal of Crystal Growth, 175/176: 935-939 (1997).
"Photoluminescence and Time-Resolved Photoluminescence Characteristics of In(x)Ga(1-x)As/GaAs Self-Organized Single- and Multiple-Layer Quantum Dot Laser Structures," K.Kamath, N.Chervela, K.Linder, T.Sosnowski, H.Jiang, T.Norris, J.Singh and P.Bhattacharya, Applied Physics Letters, 71, (1997).
"Conduction Band Spectra in Self-Assembled InAs/GaAs Dots: A Comparison of Effective Mass and an Eight-Band Approach," H.Jiang and J.Singh, Applied Physics Letters, 71, (1997).
"Tunneling Injection Lasers: A New Class of Lasers with Reduced Hot Carrier
Effects," P.Bhattacharya, J.Singh, H.Yoon, X.Zhang, A.Gutierrez-Aitken, and
Y.Lam, IEEE Journal of Quantum Electronics, 32,
1620-1629 (1996).
"Finite-Difference Time-Domain analysis and Experimental Examination of the Performance of a Coupled-Cavity MQW Laser/Active Waveguide at 1.54 mu m,"
Y.Yuan, R.Jambunathan, J.Singh and P.Bhattacharya, IEEE Journal of Quantum
Electronics, 33, 408-415 (1997).
"High Power Laser Semiconductor Interactions: A Monte Carlo Study for
Silicon," K.Yeom, H.Jiang and J.Singh, Journal of Applied Physics
, 81, 1807-1812 (1997).
"Time Domain Optical Wave Propogation in Disordered and Non-Uniform
Guiding Structures," I.Vurgaftman, P.N.Freeman, P.Bhattacharya and J.Singh
IEEE Jounal of Quantum Electronics, 32, 2095 (1996).
"High Field Thermal Noise of Holes in Silicon: The Effect of Valence Band
Anisotropy," J.M.Hinckley and J.Singh, Journal of Applied Physics,
80, 6766 (1996).
"Effects of Non-Uniform Charge Injection on Gain, Threshold Current, and
Linewidth Enhancement Factor for a 1.55 mu m InP Based Multiple Quantum
Well Laser," R.Jambunathan and J.Singh, Journal of Applied Physics, 80, 6875 (1996).
"Room Temperature Intra-Band Lasing in Quantum Dot Arrays Placed in High
Photon Density Cavities--A Theoretical Study," J.Singh, Superlattices and Microstructures, 20, 499 (1996).
"Large Blue Shift in the Photoluminescence of Pseudomorphic InGaAs/GaAs
Quantum Wells Grown in Patterned (100) GaAs Grooves and Ridges with Vertical
Sidewalls," K.Kamath, J.Phillips, J.Singh, and P.Bhattacharya, Journal of
Vacuum Science Technology, B, 14, 2312 (1996).
"Amplitude-Modulation Characteristic of Barrier-Reservoir and Quantum-Well
Electron-Transfer (BRAQWET) Modulators," P.N.Freeman, P.Bhattacharya, M.Jaffe
and J.Singh, IEEE Journal of Quantum Electronics, 32,
1161 (1996).
"Calculation of Electron and Hole Impact Ionization Coefficients in SiGe
Alloys," K.Yeom, J.M.Hinckley and J.Singh, Journal of Applied Physics,
80, 6773 (1996).
"Free Carrier Absorption as a Probe of Carrier Dynamics: A Monte Carlo
Study for Silicon," H.Jiang and J.Singh, Applied Physics Letters, 70, 1834 (1997)>
"The Effect of Strain on Hot-Electron and Hole Longitudinal Diffusion and
Noise in Si and Si(0.9)Ge(0.1)," K.Yeom, J.M.Hinckley and J.Singh, Journal of Applied Physics, 78, 5454 (1995).
"Polarization Dependence of the Absorption Coefficient for an Array of
Strained Quantum Wires," I.Vurgaftman and J.Singh, Journal of Applied
Physics, 47, 4931 (1995).
"Optical Control of 14GHz MMIC Oscillators Based on InAlAs/InGaAs HBT's
with Monolithically Integrated Optical Waveguides," P.Freeman, X.Zhang, I.Vurgaftman, J.Singh and P.Bhattacharya, IEEE Trans. Elect. Dev., 43, 373 (1996).
"Surface Phenomena and Kinetics of Si(1-x)Ge(x)/Si(0x1) Growth by
Molecular Beam Epitaxy Using Si(2)H(6) and Ge/GeH(4)," F.C.Zhang, J.Singh
and P.Bhattacharya, Journal of Vac. Sci. Technol., B14,
May (1996).
"Hot Hole Relaxation in the SiGe System," K.Yeom, J.M.Hinckley and J.Singh, Journal of Applied Physics, 79, 2790 (1996).
"Influence of Pseudomorphic Base-Emitter Spacer Layers on Current-Induced
Degradation of Beryllium-Doped InGaAs/InAlAs Heterojunction Bipolar Transistors," K.Zhang, X.Zhang, P.Bhattacharya and J.Singh, IEEE Trans. Electron. Dev.
, 43, 8 (1996).
"A Cold InP-Based Tunneling Injection Laser with Greatly Reduced Auger
Recombination and Temperature Dependence," H.Yoon, A.L.Gutierrez-Aitken, R.Jambunathan,J.Singh and P.Bhattacharya, IEEE Photonics Tech. Lett. 7, 974-976 (1995).
"Anisotropic High Field Transverse Differential Mobility of Holes in
Silicon," J.M.Hinckley and J.Singh, Appl. Phys. Lett., 67 2966 (1995).
"Anisotropic High Field Diffusion of Holes in Silicon," J.M.Hinckley
and J.Singh, Appl. Phys. Lett., 68, 2727 (1995).
"Laser Induced Impact Ionization in Semiconductors: A Monte Carlo Study
for Silicon," B.Kochman, K.Yeom and J.Singh, Appl. Phys. Lett.,
68, 1936 (1996).
"Possibility of Room Temperature Intra-Band Lasing in Quantum Dot Structures
Placed in High-Photon Density Cavities," IEEE Photonics Techn. Lett.,
8, 488 (1996).
"Spatial and Spectral Characteristics of Spontaneous Emission from
Semiconductor Quantum Wells in Microscopic Cylindrical Cavities," I.Vurgaftman and J.Singh, Appl. Phys. Lett., 67 3865 (1996).
"Dependence of Al(0.48)In(0.5)As Schottky Diode Properties on Molecular
Beam Epitaxial Growth Temperature," Appl. Phys. Lett., 68, 220 (1996).
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