MECHANISM RESPONSIBLE FOR THE SEMIINSULATING PROPERTIES OF LOW-TEMPERATURE-GROWN GAAS

The mechanism responsible for the semi-insulating properties of low-te mperature-grown GaAs is investigated by determining the concentration of arsenic antisite (As(Ga))-related defects in the material. The conc entrations of the defects in neutral and positively charged states, As (Ga)0 and As(Ga)+, are determined by near-infrared absorption and magn etic circular dichroism of absorption, respectively. Materials grown a nd annealed at different temperatures are investigated. We find that t he defects are abundant in all samples studied, with the concentration of As(Ga)0 higher than that of As(Ga)+ defects. The results indicate that the defects can account for the pinning of the Fermi energy and c onsequently also the semi-insulating properties of the material. (C) 1 994 American Institute of Physics.