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Semiconductor Physics
- Full-Band Monte Carlo Models for Advanced Transport Simulation in Silicon
- Heterojunctions, Transport, Ion Implantation, and Defects in III-V Semiconductors
- High Field Transport of Free Carriers at Interfaces
- Scattering Time Engineering in Quantum Devices
- Scalable Spin-Qubit Circuits with Quantum Dots
^ Full-Band Monte Carlo Models for Advanced Transport Simulation in Silicon
K. Hess,* U. Ravaioli,* A. Kepkep, B. Winstead
Semiconductor Research Corp.
(Conducted in the Coordinated Science Laboratory)
The goal of this research is to develop full-band Monte Carlo simulation software for the analysis of hot-electron effects in advanced integrated silicon devices. Besides being used for self-consistent device simulation, the Monte Carlo software will provide calibration for faster simulation tools designed for the solution of the Boltzmann equation in the spherical harmonics expansion approximation or in the scattering matrix formalism. The research has focused on the development of improved physical models for interface scattering and carrier-carrier interaction, as well as efficient coupling with standard CAD tools used in industry.
^ Heterojunctions, Transport, Ion Implantation, and Defects in III-V Semiconductors
K. Hess,* Y. Liu, W. Ng, W. McMahon
U.S. Office of Naval Research, N00014-89-J-1470
(Conducted in the Coordinated Science Laboratory)
A simulation tool for quantum-well laser diodes is developed. Particular emphasis is on electronic transport around and capture into the quantum wells. We also include the heating of quantum-well electrons and spectral as well as special hole burning. The resulting simulation tool (MINILASE II) covers, therefore, all known nonlinear gain effects. Currently we are generalizing MINILASE II to simulate vertical cavity surface-emitting lasers. Work on quantum-dot and quantum-wire lasers is also planned.
^ High Field Transport of Free Carriers at Interfaces
K. Hess,* F. Register, A. O. Haggag
U.S. Army Research Office, DAAL03-86-K-0099
(Conducted in the Coordinated Science Laboratory)
In this research we are studying the ultimate limitations of electronic transport in silicon and III-V compounds including superlattices and the corresponding potential for new devices, as well as the advantages of including heterolayers in conventional devices. The theoretical approach includes Monte Carlo simulations and explicit solutions of the Boltzmann equation. We are also developing a new algorithm to solve problems of quantum transport in the presence of dissipation. Currently, we apply our methods to the newly found phenomenon of reduced hot electron degradation in devices based on the deuterium isotope effect.
^ Scattering Time Engineering in Quantum Devices
J. P. Leburton,* W. Cheng, S. Naran
U.S. Army Research Office, DAAD19-99-1-0129
(Conducted in the Coordinated Science Laboratory)
This theoretical research addresses major transport issues in quantum dot (QD) nanostructures. We emphasize the effects of 3-D confinement on the transport characteristics of systems of QDs. We specifically propose to investigate quantum transport through single, coupled, and arrays of QDs by simulating the electronic and phonon properties of the nanostructures by taking into account size, shape, and materials variations to modify the scattering processes and ultimately the transport characteristics of the structures. We use advanced numerical techniques featuring a 3-D self-consistent Poisson-Schroedinger solver within the density functional theory, continuous strain models, and confined phonon models developed by our group.
^ Scalable Spin-Qubit Circuits with Quantum Dots
J. P. Leburton,* P. Matagne, R. Ravishankar, L. Zhang
DARPA-QuIST program, DAAD19-01-1-0659
This research is aimed at achieving a scalable elementary spin-qubit circuit for quantum computing that is based on the manipulation of electron spins in coupled III-V semiconductor quantum dots (QDs). We take advantage of the advanced technology for planar and lateral QDs AlGAs/GaAs heterostructures and the fact that the electron effective mass is small, which eases the conditions for quantum confinement. Moreover, III-V materials enjoy long spin coherence times, which is of utmost importance for preserving quantum information over many qubit operations. For this purpose, we have assembled an international research team involving the University of Basel, the University of Delft, Harvard University, Princeton University, and Tokyo University. Team members have complementary expertise in the physics of quantum computation and spintronics in nanostructures. These areas of expertise are fully integrated into a coherent and interactive effort, leading to the realization of an elementary qubit circuit.
