(AASERT-92) Arsenic Cluster Engineering for High Speed Photoconductors.
Abstract
GaAs epilayers grown at low substrate temperatures by molecular beam epitaxy contain arsenic antisites and gallium vacancies. With anneal these point defects form arsenic precipitates. We have investigated GaAs epilayers with a wide range of excess arsenic concentrations and anneal conditions to study the role of the point defects and arsenic precipitates in carrier trapping and recombination: we have determined the electron and hole capture cross sections for the arsenic antisite in LTG-GaAs of sigma n = 7xa10(exp-15) sq cm and sigma p = 6x10(exp -17) sq cm respectively. We have also shown the concentration of arsenic antisites in annealed LTG-GaAs is not sufficient to account for the short carrier lifetimes. In addition, the recombination of electron-hole pairs in annealed LTG-GaAs is single exponential, which would not be the case for a trap with a large difference in electron and hole capture cross-sections as the arsenic antisite. Since the arsenic antisites and gallium vacancies are disappearing with anneal, and it is unlikely another defect of significant concentration is being formed1 we conclude that the arsenic precipitates are the source of the short carrier lifetimes. Also, since the differential transmission transients become single exponential with anneal and formation of the arsenic precipitates, the arsenic precipitates must have comparable electron and hole capture cross-sections.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1997
- Accession Number
- ADA325684
Entities
People
- Michael R. Malloch
Organizations
- Purdue University