Annealing behaviour of low temperature grown GaAs investigated by SIMS

Epitaxial growth of LT GaAs at low temperatures of around 200degC with an excess of a group V element leads to a non-stoichiometric layer properties. The electrical and optical parameters of such a layer are significantly changed and strongly depend on the post growth annealing conditions. To find the optimal annealing temperature of LT GaAs layers subsequent secondary ion mass spectroscopy (SIMS) depth profile was investigated. The contaminants in a form of C and O are determined, which alter due to temperature treatments the SIMS depth profile. Segregations of C and O near surface regions as a function of annealing of the LT GaAs structures were observed. The heat treatment causes C concentration out-diffusion in the dependence of annealing temperatures. It was confirmed that these two elements belong to the dominant dopants in the LT GaAs layers