GaN/Al_2O_3(0001)的匹配机制及氮化的作用

在Ａｌ２Ｏ３（０００１）衬底上用ＭＯＣＶＤ（金属有机物气相沉积）方法进行了ＧａＮ的外延生长，通过Ｘ射线衍射（同步辐射源）研究了ＧａＮ和Ａｌ２Ｏ３（０００１）的匹配关系。结果表明，经充分氮化的衬底上，ＧａＮ以单一的匹配方式沿［０００１］方向生长；在Ａｌ２Ｏ３（０００１）衬底未经氮化或氮化不充分时，不同程度地出现了其它三种绕〈１１２０〉晶带轴倾斜一定角度的匹配位向。指出了ＧａＮ／Ａｌ２Ｏ３（０００１）的几种匹配方式的晶体学规律。ＧａＮ绕〈１１２０〉晶带轴倾斜的匹配方式是其外延生长过程中降低和Ａｌ２Ｏ３（０００１）的晶格失配、释放界面应变的重要机制之一。

Epitaxial Matching Orientations of GaN with Bare and Nitridated Al 2O 3(0001) Substrates

GaN thin films were grown by metal organic chemical vapor deposition on Al 2O 3(0001) substrates, the epitaxial relationships between GaN and Al 2O 3(0001) were examined by a X ray(synchrotron radiation source) diffraction method. Results revealed that GaN grown on the well nitridated substrates exhibited the popular crystallographic orientation with direction perpendicular to the Al 2O 3(0001), while those grown on the bare or insufficiently nitridated substrates proved to have three other orientations which rotated by certain angles around its in respect to the popular one. The orientation tiltings were suggested to be one of the inportant mechanisms by which GaN films could match better with Al2O3(0001) substrates and relax the interfacial strain effectively.