Study of GaN thin layers subjected to high-temperature rapid thermal annealing

A detailed study of the effect of rapid thermal annealing in a N2 or Ar atmosphere on the properties of thin GaN layers grown by molecular-beam epitaxy on sapphire substrates was performed. After rapid thermal annealing, an enhancement of the crystal quality of such films was observed. Low-temperature photoluminescence measurements revealed a substantial increase in impurity recombination near the fundamental absorption edge after a rapid high-temperature anneal in a nitrogen atmosphere. A significant decrease in the impurity photoluminescence of the GaN films with protective SiO2 coatings was observed following the anneals.