Effect of ambient on photoluminescence from GaN grown by molecular-beam epitaxy

We report the investigation of reversible-transient effects in photoluminescence (PL) of GaN layers in different measurement ambients including air, oxygen, nitrogen, and hydrogen. While the presence of air and oxygen led to similar amounts of significant decrease in overall luminescence, nitrogen and hydrogen produced a much smaller effect. Data on the different behaviors of the near-band-edge and the deep-level (yellow luminescence (YL)) spectral components of the luminescence with change from vacuum to the various ambient gases will be presented. A redshift of the deep-level luminescence band was noticed in oxygen or air ambient that has been attributed to a decrease of the band bending.