Metastability of defects in p-GaAs grown from a Ga-rich melt

We report the observation of metastability for defects in Si-doped p-GaAs g rown from a Ga-rich melt. A configuration change occurs suddenly at a criti cal temperature (near 120 K) during cooldown scans, giving rise to disconti nuous deep-level transient spectra. A similar phenomenon was observed on el ectron-irradiated float-zone-refined Si and explained in terms of entropy v ariations in the configurational space. We believe that the metastability f ound in the p-GaAs sample is also due to a barrierless transformation of de fect configuration, driven by variations in both entropy and the charge sta te of Ga-As. (C) 2001 American Institute of Physics.