利用氫化物氣相磊晶法成長非極性氮化鎵之研究

Abstract

本論文利用氫化物氣相磊晶法在有機金屬氣相沉積法成長的模板上來探討非極性氮化鎵的成長機制與分析，藉由調變不同參數，像載子氣體、氯化氫流量、成長溫度及五三比來改善表面形貌，並且提升晶體品質。為了簡化製程及減少外來污染等目的，進一步利用氫化物氣相磊晶系統直接在藍寶石基板上成長成長非極性氮化鎵，流程包括氮化處理、低溫氮化鎵緩衝層成長、高溫氮化鎵磊晶層成長，且完全在同一個腔體中完成。在此部分，重點主要是在研究低溫緩衝層的形貌影響，並分析後續氮化鎵磊晶的晶體品質及光學特性。X 光繞射與光激螢光量測結果顯現以低壓且低五三比成長緩衝層有對後續磊晶有較佳的晶體品質及光學特性。

In this research, we first investigated the growth mechanism of non-polar a-plane GaN thick films on MOCVD template by hydride vapor phase epitaxy (HVPE). The surface morphology and crystal quality of a-plane GaN thick films were studied by various growth parameters, such as carrier gas, HCl flow rate, growth temperature, and V/III ratio. Furthermore, a-plane GaN thick films were also deposited on bare sapphire substrates. The purposes of using bare sapphire substrate are to simplify the process, lower the MOCVD cost, and prevent pollution in the environment. Basic process includes H2 cleaning, nitridation, LT-GaN buffer layer growth, HT-GaN growth. In this part, we investigated the influence of the LT-GaN buffer layer on the quality of the GaN by the study of the surface morphology of the buffer layer, and the crystalline and analysis optical properties of the subsequently grown a-plane GaN. X-ray diffraction and photoluminescence results reveal that better crystalline and optical quality could be obtained using lower Pressure and lower V/III ratio to growth buffer layer .