Photoluminescence of GaN layers studied with two-color spectroscopy

摘要

We report on the results of an investigation of GaN layers by two-color spectroscopy in the visible and the near infrared (IR) (0.9-2 μm) or mid-infrared (6-18 μm). After primary band-to-band excitation, a secondary beam is used with photon energy to matching ionization energy of levels in the gap. Photoluminescence spectra obtained with and without additional IR illumination are compared for different photon energies. The impact of IR radiation on the donor-related emission is discussed, and the involvement of deep mid-gap states is postulated.