We use positron annihilation to study vacancy defects in GaAs grown at low temperatures (LT–GaAs). The vacancies in as-grown LT–GaAs can be identified to be Ga monovacancies, according to their positron lifetime and annihilation momentum distribution. The charge state of the vacancies is neutral. This is ascribed to the presence of positively charged antisite defects in vicinity to the vacancies. Theoretical calculations of the annihilation parameters show that this assignment is consistent with the data. The density of is related to the growth stoichiometry in LT–GaAs, i.e., it increases with the As/Ga beam equivalent pressure (BEP) and saturates at for a BEP⩾20 and a low growth temperature of Annealing at removes Instead, larger vacancy agglomerates with a size of approximately four vacancies are found. It will be shown that these vacancy clusters are associated with the As precipitates formed during annealing.
Defect identification in GaAs grown at low temperatures by positron annihilation
J. Gebauer, F. Börner, R. Krause-Rehberg, T. E. M. Staab, W. Bauer-Kugelmann, G. Kögel, W. Triftshäuser, P. Specht, R. C. Lutz, E. R. Weber, M. Luysberg; Defect identification in GaAs grown at low temperatures by positron annihilation. J. Appl. Phys. 15 June 2000; 87 (12): 8368–8379. https://doi.org/10.1063/1.373549
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