氮化镓光辅助湿法刻蚀后的位错密度估算

发展了一种显示与估算氮化镓 (Ga N)位错密度的光辅助湿法刻蚀与原子力显微镜相结合的方法。所用 Ga N采用射频等离子体辅助的分子束外延技术 (RF-plasma MBE)生长 ,腐蚀液为 KOH水溶液。结果发现 ,使用 5 .0 M的 KOH溶液刻蚀 5分钟的 Ga N,其 AFM图谱上出现了非常明显的“小坑”,且“小坑密度”的量级与Ga N样品的位错密度量级相当。采用 X-ray衍射的二维三轴图谱 (TDTAM)研究 Ga N的马塞克柱状生长与缺陷 ,并延用文献报道的方法估算其位错密度 ,所得位错密度的结果与“小坑密度”一致。验证了“小坑”即为被刻蚀了的 Ga N位错。这样 ,对 RF-plasma MBE生长的 Ga N样品的位错密度估算 ,就多了一个有更广适用范围的测量方法

AFM Measurement and Dislocation Density Estimation of GaN Etched by Photo-assisted KOH Solution

In this paper, a new method of dislocation density estimation of GaN by using wet etching and AFM measurement was reported. Using photo assisted KOH solution, the GaN grown by RF plasma MBE was etched and the “pits” were observed in AFM images. The observed “pits” density seems to be approximated to the dislocation density of GaN. From comparing the defects in the Two Dimensional Three Axes Mapping (TDTAM) of X ray diffraction measurement to the GaN dislocation density by using conventional method, the same results were obtained. This confirmed that the GaN dislocation density could be estimated by the “pits” density. Therefore, a convenient method to estimate the dislocation density of GaN grown by RF plasma MBE was established.