A systematic investigation of GaAs layers grown at low temperatures was carried out by means of positron annihilation. The vacancy defects in undoped as-grown material were identified to be mainly Ga vacancies (VGa) by comparing the annihilation parameters to those of Ga vacancies in highly Si-doped GaAs. The characteristic S parameter for positron annihilation in Ga vacancies was determined to be S(VGa)=1.024(1). The VGa concentration increases up to 1018 cm-3 by decreasing the growth temperature to 200 °C. The vacancy concentration can account for the compensation of AsGa+ antisites as was previously assumed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)