A quantitative analysis of the surface and subsurface damage to gallium nitride (GaN) substrate from precise mechanical polishing with diamond abrasives and characterizations of their removal by the chemical mechanical polishing (CMP) process with colloidal silica slurry was performed. The cross-sectional transmission electron microscopy showed that the highly-defected regions were approximately 200 nm from the surface. The cathodoluminescence (CL) imaging showed that the subsurface damage layers were a cluster of extremely high-density networks of line-shaped defects. The depth-resolved and CMP-process-time-resolved CL imaging sensitively detected that while the high defect density subsurface damage layers were approximately 200 nm from the surface some of the subsurface damage reached over 1 μm in depth. Using the high-resolution x-ray diffraction, the CMP process was shown to decrease the dislocation densities, enlarge the correlation length, and release the compressive stress in the crystals induced by the mechanical polishing process. Improvement in these crystal properties was found to occur by removing the highly-defected surface regions.

对使用金刚石磨料进行精确机械抛光对氮化镓（GaN）衬底的表面和亚表面损伤进行了定量分析，并通过使用胶体二氧化硅浆料的化学机械抛光（CMP）工艺去除了氮化镓（GaN）衬底，对它们的表征进行了表征。横截面透射电子显微镜显示高偏转区域距离表面约200 nm。阴极发光（CL）成像表明，表面下的破坏层是线状缺陷的极高密度网络的簇。深度分辨和CMP处理时间分辨CL成像灵敏地检测到，虽然高缺陷密度的次表面损伤层距离表面约200 nm，但一些次表面损伤的深度超过1μm。使用高分辨率的X射线衍射，表明CMP工艺可降低位错密度，增大相关长度并释放由机械抛光工艺引起的晶体中的压应力。发现通过去除高度挠曲的表面区域可以改善这些晶体的性能。