Abstract The crystalline quality of AlN epitaxial layers on sapphire substrates was improved by introducing trimethylgallium (TMGa) pulse flow into the growth of AlN nucleation layers. It was found that the density of both screw- and edge-type threading dislocations could be significantly reduced by introducing the TMGa pulse flow. With increasing TMGa pulse flow times, the lateral correlation length (i.e. the grain size) increases and the strain in the AlN epilayers changes from tensile state to compressive state. Unstrained AlN with the least dislocations and a smooth surface was obtained by introducing 2-times TMGa pulse flow. The crystalline improvement is attributed to enhanced lateral growth and improved crystalline orientation by the TMGa pulse flow.

中文翻译：

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通过将 TMGa 脉冲流引入成核阶段，提高了蓝宝石上 AlN 外延层的结晶质量

摘要 通过在AlN成核层的生长中引入三甲基镓（TMGa）脉冲流，提高了蓝宝石衬底上AlN外延层的结晶质量。发现通过引入 TMGa 脉冲流可以显着降低螺旋型和刃型螺纹位错的密度。随着TMGa脉冲流动时间的增加，横向相关长度（即晶粒尺寸）增加并且AlN外延层中的应变从拉伸状态变为压缩状态。通过引入 2 次 TMGa 脉冲流获得具有最少位错和光滑表面的无应变 AlN。结晶改善归因于 TMGa 脉冲流增强的横向生长和改善的结晶取向。