采用高分辨XRD对m面GaN位错特性的研究

Study on the Dislocation of Epitaxial m-GaN Films Revealed by High Resolution X-Ray Diffration

利用高分辨X射线衍射方法,分析了在LiAlO2(100)面上采用金属有机化学气相沉积生长的m面GaN薄膜的微观结构和位错。采用对称面扫描和非对称面扫描等方法研究了晶面倾转角、面内扭转角、横向和垂直关联长度等,由此得到螺位错和刃位错密度。考虑到m面GaN的各向异性,将〈0001〉晶向定义为0°方向,与之垂直的方向为90°方向,分别按0°和90°两个不同方向进行X射线衍射的研究。0°方向和90°方向螺位错密度分别为1.97×1010、7.193×109cm-2,0°方向螺位错密度较大;0°和90°方向刃位错密度分别为3.23999×1010、7.35068×1010cm-2,90°方向刃位错密度较大,显示了非极性GaN薄膜各向异性的特征。

The microstructure and dislocation of m-GaN film grown on LiAlO2(100)by metalorganic chemical vapor deposition(MOCVD)were studied using high resolution X-ray diffraction.The mosaic tilt,twist and correlation lengths of GaN film were determined by using symmetrical and asymmetrical reflections.Deducing from these results,the density of screw-type and edge-type dislocations can be obtained.Considering anisotropy of the m-GaN film,it was defined the 〈0001〉 direction as the direction of 0° and the direction which was perpendicular to the direction of 0° as the direction of 90° were studied.The sample properties were studied using X-ray diffraction in those two different directions,respectively.The screw-type dislocations density in 0° direction is 1.97×1010 cm-2,larger than that in 90°direction which is 7.193×109 cm-2.The edge-type dislocations density in 0° and 90° direction is 6.356 13×1010cm-2,7.991 35×1010cm-2,respectively.All these differences indicate the anisotropy of m-GaN.