氮化鎵基板經化學機械研磨後損害層觀察與去除之研究

Abstract

本論文主要目的是氮化鎵基板表面粗糙度與表面下損害層之研究，期望能夠取得可供再成長之氮化鎵基板。機械研磨製程利用AFM表面粗糙度探討取得理想參數，使得表面粗糙度能夠小於1nm。此外損害層探討發現可以利用PL的NBE強度與P/Y值的比例去觀察之，亦可利用CL的俯視圖與側視圖去觀察有無損害層，並且利用TEM影像去再次證明PL與CL的現象；利用ICP可以有效去除機械研磨造成的損害層，而細微化學機械研磨製程對於損害層的去除亦是有其功效，但參數還必須做調整；最後利用適當表面處理而成功的在MOCVD上磊晶成長出近紫外光LED。

In this work , the major purpose was to study the surface roughness and sub-surface damage of GaN substrates and expect to obtain epi-ready GaN substrate. We studied the surface roughness by atomic force microscope to acquire the optimum parameter of mechanical polish process, then the RMS surface roughness less than 1nm that we done. In the research of the damage, we had to observe the damage by the near band edge intensity and the intensity ratio of the NBE emission to yellow luminescence of photoluminescence (PL). And, the plane view and cross section image of cathodoluminescence (CL) was applied to analysis the surface damages. Furthermore, transmission electron microscope measurement was used to test and verify the phenomenon by the PL and CL measurement; the Inductively Coupled Plasma treatment on the mechanically polished samples effectively removed the polishing-induced damage. And, the subsurface damage could be removed by fine chemical mechanical polish, but the parameter needed to be adjusted. Finally, it was successful to growth the near UV LED on GaN substrate with suitable surface treatment.