Electrical properties of Fe in GaAs

Abstract

GaAs has been doped with Fe by diffusion and by liquid-phase epitaxy. The deep level introduced has an optical cross section for excitation of holes to the valence band with one threshold at 0.46 eV and another at about 0.85 eV. By combining those data with previous measurements of internal transitions between the ground state and an excited state, the level position in the gap is established. Optical excitation of electrons to the conduction band is below the limit of detection. The cross section for capture of electrons is nearly temperature independent with a value of about 10−19 cm2 at 200 K, and the thermal activation energy for emission of holes is 0.54 eV after T2 correction.