Carrier Dynamics and Defects in GaAs and Related Photoconductors
Abstract
Our program on Carrier Dynamics and Defects in GaAs and Related Photoconductors concentrated on two major thrusts: the study of the physical processes involved in trapping and recombination of carriers in low-temperature-MBE-grown (LT) GaAs, and the development of high-speed photoconductive probes. By using femtosecond time-resolved optical spectroscopy, with both above-gap and below-gap excitation and probing, we were for the first time able to measure the separate trapping times for electrons and holes, determine the lifetimes of the carriers within the traps, observe trap saturation, and observe an unusually large Auger recombination rate caused by the high density of crystal defects in LT-GaAs. The affects of surface passivation, materials growth conditions (temperature, annealing, and implantation) were studied. Two kinds of photoconductive devices were developed. A freely positionable voltage probe with picosecond time response, unprecedented sensitivity (30 nanovolts per root hertz), and high (micron) spatial resolution was developed. The same technology was adapted to develop a novel miniature source for terahertz radiation. The photoconductive probe was applied to the study of millimeter-wave devices and circuits.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 15, 2000
- Accession Number
- ADA375403
Entities
People
- John F. Whitaker
- Theodore B Norris
Organizations
- University of Michigan