利用金属有机化合物气相沉积(MOCVD)在蓝宝石衬底上生长了高阻GaN薄膜。对GaN成核层生长的反应室压力、生长时间和载气类型对GaN缓冲层电学特性的影响进行了分析。实验结果表明, 延长GaN成核层的生长时间, 降低成核层生长时的反应室压力, 载气由H2换为N2都会得到高阻的GaN缓冲层。样品的方块电阻Rs最高为2.49×1011 Ω/□。以高阻GaN样品为衬底制备了AlGaN/AlN/GaN 结构HEMT器件, 迁移率最高达1 230 cm2/(V·s)。

High resistance GaN thin film was grown on sapphire (0001) substrates using metal-organic chemical vapor deposition (MOCVD). Effect of the GaN nucleation layer growth parameters, including reactor pressure, species of carrier gas and growth time, on the electrical characteristics of the following grown GaN buffer was investigated. It is found that GaN films epitaxially grown on the GaN nucleation layers deposited at a relatively lower pressure tend to have a high resistance.High resistance GaN buffer layer can also be prepared by extending growth time of the nucleation layer (i.e. increasing the thickness of nucleation layer) or by using N2 instead of H2 as carrier gas during the growth of nucleation layer. GaN layers with a sheet resistance as high as 2.49×1011 Ω/□ was obtained. These layers were used as templates for the preparation of epi-wafers with AlGaN/AlN/GaN hetero structures, which were used to fabricate high electron mobility transistors (HEMTs). The highest mobility of these samples reaches to 1 230 cm2/(V·s).