Metastable defects in Be-doped AlxGa1−xAs

Abstract

Deep-level transient spectroscopy has been used to study metastable defects in Be-doped Alx Ga1−x As grown by molecular-beam epitaxy. The metastability manifests itself by the appearance of different spectra depending upon whether the sample is cooled from a high temperature with zero bias or a reverse bias applied to it. The defects are found in concentrations of 1015 cm−3 in a sample doped with 1018 Be cm−3 and in much lower concentrations in a 1017 Be cm−3 sample. Isochronal annealing experiments indicate that the defect is multistable and that it is best modeled as a mobile interstitial which can reside at several sites near an acceptor. The activation energies for these defects are between 0.2 and 0.5 eV above the valence band.