横向外延GaN结晶质量的同步辐射研究

Synchrotron X-ray diffraction analysis of epitaxial GaN layer laterally overgrown

采用同步辐射X光衍射技术研究了α -Al2 O3(0 0 0 1)衬底上横向外延GaN的结构特征。发现横向生长区的GaN(0 0 0 1)晶面与窗口区的GaN(0 0 0 1)晶面在垂直掩模方向上存在取向差。ω/2θ联动扫描发现横向生长区的GaN的衍射峰半高宽约为窗口区GaN的一半 ,这表明横向外延生长技术在降低GaN穿透位错密度的同时 。

The GaN layer grown by epitaxial lateral overgrowth on sapphire (0001) has been investigated by synchrotron X-ray diffraction. The results show that ELO GaN stripes bend towards the SiN x mask in directions perpendicular to the stripe direction. This lead to the GaN (0001) crystal planes in the ' wings' (overgrown GaN) exhibit crystallographic tilts away from those in the ' window' (seed) regions. The GaN (0002) diffraction was used to determine the grain sizes in the wing region and window region, respectively. It is found that the grain size in the wing region increases about three times comparing to those in window region.