利用化學機械研磨與熱退火處理氮化鎵基板表面之研究

Abstract

本論文主要目的是利用化學機械研磨與熱退火處理氮化鎵基板表面之研究，以期 取得提供再成長的氮化鎵基板。由PL和CL量測可知化學機械研磨(CMP)與熱退火兩者都能有效去除機械研磨所產生的損害層，然而熱退火造成的表面粗糙程度是不可接受的，熱退火溫度越高表面形貌越粗糙。經過長時間CMP研磨可以得到低粗糙度無刮痕的樣品表面，且表面粗糙度可小於1.5nm以下。最後我們取得氮化鎵基板最佳CMP製程參數，而且成功的利用MOCVD在無損害層的氮化鎵基板上成長品質良好的u-GaN。我們再藉由AFM、Nomarski、XRD和CL量測去驗證u-GaN品質。

In this work, the major purpose was to study the surface treatments of GaN substrates by chamical mechanical polish(CMP) and thermal anneal and expect to obtain epi-ready GaN substrate. Both photoluminescence and cathodoluminescence indicate that CMP and thermal anneal both effectively removed the polishing-induced damage layer. However, thermal anneal result in an unacceptably rough surface morphology and the higher the anneal temperature, the rougher surface become. The longtime CMP polished surface shows low roughness with no scratches and produced a root-mean -square (RMS) surface roughness less than 1.5nm. Finally we acquire the optimal CMP process parameter for GaN substrates and it was successful to grow high quality u-GaN by MOCVD on GaN substrates with no damage layer. We can evidence the quality of u-GaN by AFM、Nomarski、XRD and CL measurements.