Study of deep level defects in <i>n</i>-GaN by the optical transmission method

Abstract

Absorption coefficient spectra are determined by optical transmission of undoped gallium nitride films, which is used for the density of states distribution. The absorption of n-type GaN in the region of photon energy lower than the band edge is regarded as attributable to the local deep defect levels. For the photoemission of electrons to the conduction band, two optical threshold energies were detected, approximately at 2.1 eV from one deep level and near 1.1 eV from one or several deep levels. Discussion is centered on the possible participation of either level in the commonly observed 2.2 eV defect luminescence transitions.