Defect control in As-rich GaAs

P. Specht, S. Jeong, H. Sohn, M. Luysberg, A. Prasad, J. Gebauer, R. Krause-Rehberg, E. R. Weber

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27 Citations (Scopus)

Abstract

The incorporation of excess As in GaAs, grown by MBE at low tempertures, produces native defects such as As antisites (AsGa), As interstitials (Asi) or Ga vacancies (VGa). These point defects dilate the lattice. Their concentrations increase with decreasing growth temperature and can be well reproduced by a careful control of the substrate temperature and the As/Ga flux ratio. The ionized [AsGa+] equals three times the [VGa]. Therefore, VGa triple acceptors are the dominant native acceptors in LT-GaAs. The ultrafast electron trapping time, measured in LT-GaAs (< 1ps below TG=230°C) was reported to correlate to [AsGa+]. In undoped LT-GaAs, however, the [AsGa+] does not exceed 10% of the total concentration of AsGa. We studied high p-doping with Be acceptors in order to achieve a larger ionization fraction of the AsGa. As a result we developed thermally stable, non-stoichiometric GaAs with subpicosecond trapping times, grown at T=275°C. The ratio [AsGa+]/[AsGa] was found to exceed 50%. However, in LT-GaAs:Be carrier capture at AsGa+ is not the only trapping mechanism, it's concentration is neither correlated to the [Be] nor to the measured trapping times.It is suggested that additional carrier capture by doubly ionized AsGa++, is taking place, caused by the lowered Fermi level due to Be-doping. The strain compensation of the large AsGa defects with the small BeGa acceptors enhances the thermal stability of the native point defects. Therefore, the thermally more stable LT-GaAs:Be offers new prospects for the application of As-rich GaAs in ultrafast optoelectronics. non-stoichiometric GaAs,.

Original languageEnglish
Pages (from-to)951-956
Number of pages6
JournalMaterials Science Forum
Volume258-263
Issue numberPART 2
DOIs
Publication statusPublished - 1997

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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