Trap signatures of as precipitates and As-antisite-related defects in GaAs epilayers grown by molecular beam epitaxy at low temperatures

Despite many separate studies of the two dominant defects, i.e., As precipitates and arsenic-antisite (As-Ga)-related traps, in GaAs epilayers grown by molecular beam epitaxy at low temperatures, they are seldom examined simultaneously. In this letter, we report the detection of both defects in electron trap spectrum obtained by zero quiescent bias voltage transient current spectroscopy. The As precipitates appear as a broad continuum of states in the lower temperature region (<280 K) of the spectra whereas the As-Ga-related defect appears as a discrete peak at a higher temperature. The As-Ga-related trap has an activation energy of 0.65 eV and a capture cross section of 9.3 x 10(14) cm(2). It is found that the trap characteristic of low temperature GaAs is strongly dependent on its growth temperature and the above mentioned defects may not dominate in some cases. (C) 1996 American institute of Physics.