Relationship Between Hydrogen-Related Metastable Defect And EL2-Level In GaAs Crystals

Abstract

AbstractThe relationship between the hydrogen-related metastable defect (M3/M4) and the EL2 level in n-GaAs crystals has been investigated. We found with various kinds of GaAs crystals that the hydrogen-related metastable couple (M3/M4), first reported by Buchwald et al., has been observed only in the crystals containing the EL2 defect. This fact was further confirmed by using LT-MBE GaAs crystals before and after rapid thermal annealing (RTA). Only in the n-LT-n sample annealed at 900°C, in which the EL2 defect was formed, the metastable couple (M3/M4) appeared upon hydrogenation. As hydrogenated, the EL2 level was passivated or dissociated. From bias-annealing experiments, the M4 level was completely annihilated by annealing at 573K, where the EL2 level was restored to its original concentration. We speculated from these results that both diffused hydrogen and preexisting arsenic antisite defect (AsGa) are responsible for the formation of the metastable defect(M3/M4).