Optimization of GaAs Photoconductive Switch Technology for Ultra Wideband Applications
Abstract
This report describes the results of a three-year research program aimed at improving the understanding of the operation of GaAs photoconductive switches that are an integral component of a high power, ultra wideband microwave generator. The research performed revealed the following results: material properties associated with the production of the GaAs wafer prior to processing are critical in determine the switches' final operating charactenstics. In particular, high dc bias-initiated breakdown was demonstrated to occur not due to surface flashover, but rather to trap-filled sites in the vicinity of the electrode contacts; the inclusion of an n+ layer near the electrodes was demonstrated in simulations to mitigate the effects of high dc bias-initiated breakdown; the use of keV to MeV range electrons impacting the GaAs resulted in the formation of new defect levels as a result of nonionizing energy loss (NIEL) processes-this led to an increase in the dc hold-off of photoconductive switches; finally, a self-consistent, two-dimensional, time-dependent, drift diffusion model was developed to simulate the response of high power photoconductive switches-persistent photoconductivity was shown to arise at high bias even under the conditions of spatial uniformity; under strong uniform illumination, the spatial nonuniformities were quenched as a result of a polarization-induced collapse in the internal fields. Experimental work was performed to fabricate prototype switches to better understand the modeling work. This was met with mixed results due to the difficulties in reproducing the fabrication process developed earlier by researchers at ARL Ongoing work is aimed at addressing this latter issue.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 19, 2000
- Accession Number
- ADA381446
Entities
People
- Edl Schamiloglu
- Naz Islam
- R. P. Joshi
Organizations
- University of New Mexico