Model study of the local vibration center related to EL2 levels in GaAs

Abstract

A tentative explanation is given for a recently reported local vibrational mode induced infrared absorption which is related to EL2 centers in GaAs. Interstitial (or off-center substitutional) oxygen is suggested to be responsible for these vibration modes. Taking lattice relaxation into account, a simple model based on the two-center bond theory is proposed and evaluated. The adequacy of this model strongly implies a relationship of EL2 centers in the measured samples with oxygen.