Accession Number : ADA325684

Title :   (AASERT-92) Arsenic Cluster Engineering for High Speed Photoconductors.

Descriptive Note : Final rept. 1 Jun 93-31 Dec 96,

Corporate Author : PURDUE UNIV LAFAYETTE IN DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Malloch, Michael R.

PDF Url : ADA325684

Report Date : APR 1997

Pagination or Media Count : 12

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.

Descriptors :   *HIGH VELOCITY, *CLUSTERING, *ENGINEERING, *PHOTOCONDUCTORS, *ARSENIC, TRANSIENTS, ANNEALING, LOW TEMPERATURE, LAYERS, GALLIUM ARSENIDES, CHARGE CARRIERS, HOLES(ELECTRON DEFICIENCIES), SUBSTRATES, TRAPPING(CHARGED PARTICLES), CRYSTALS, POINT DEFECTS, TRANSMITTANCE, ELECTRONS, CROSS SECTIONS, VACANCIES(CRYSTAL DEFECTS), RECOMBINATION REACTIONS, CONCENTRATION(CHEMISTRY), ELECTRON CAPTURE, PRECIPITATES, MOLECULAR BEAM EPITAXY.

Subject Categories : Inorganic Chemistry
      Electrical and Electronic Equipment
      Crystallography
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE