A comparative study of high- and low-temperature AlN interlayers and their effect on the properties of GaN epilayers prepared by metal organic chemical vapour deposition on (00•1) plane sapphire substrates was carried out using high-resolution X-ray diffraction, photoluminescence and Raman spectroscopy. It was found that the crystalline quality of GaN epilayers was improved significantly by using high-temperature AlN interlayers, which prevented threading dislocations from extending; especially edge-type dislocations. Results based upon photoluminescence and Raman measurements demonstrated that there were greater compressive stresses in GaN epilayers with high-temperature AlN interlayers.

Comparative Study of Different Properties of GaN Films Grown on (0001) Sapphire using High and Low Temperature AlN Interlayers. J.S.Xue, Y.Yue, J.C.Zhang, J.Y.Ni: Chinese Physics B, 2010, 19[5], 057203