非極性氮化鎵薄膜成長機制探討及光電特性分析研究

Abstract

氮化鎵(GaN)與其合金氮化銦鎵(InGaN)及氮化鋁鎵(AlGaN)技術開發在過去十年成功快速的發展，相關的應用如可見光及紫外光發光二極體，藍/紫光雷射二極體及高功率電子元件都是建立在這一系列的材料基礎上。這些應用絕大多數是建立在c-plane薄膜上，然而隨著應用面持續的開發及高品質元件需求的增加，c-plane氮化鎵薄膜極性的問題也漸漸的被各研究單位所重視。 傳統氮化鎵(c-plane)薄膜因為結構的不對稱性，造成異質介面形成時產生的量子侷限效應(QCSE, Quantum Confined Stark Effect)。當量子侷限效應產生時，會將低內部的量子效應，並且光譜會產生紅移的現象。本研究目的在建立非極性氮化鎵磊晶技術，並針對其成長機制及量子侷限效應作詳細的探討。 本計畫將分年逐步執行，第一年主要的工作放在A-Plane、M-Plane磊晶成長機制的研究上。我們將在相同的成長條件下，同時成長A-Plane、M-Plane及C-plane之氮化鎵薄膜，並針對A-Plane、M-Plane及C-plane之氮化鎵薄膜成長機制進行研究。第二年之主要研究工作放在降低磊晶缺陷。我們將利用側向磊晶技術、奈米遮罩技術及陽極氧化鋁技術嘗試將低磊晶的缺陷。第三年我們將進行多層量子井的製作與研究，重點將放在電子電洞對複合機制研究上。我們將利用PL及CL量測薄膜的品質，由TEM看缺陷的型態，並搭配DLTS量測系統找出缺陷的參數，搭配SEM看各區域的內部量子效應分佈與 threading dislocation或stacking fault密度是否有關。最後我們將利用先前的研究成果，配合HVPE厚膜成長技術開發單晶非極性氮化鎵基板。

Gallium nitride and its alloys with indium and aluminum nitride have attracted significant attention in recent years due to their successful incorporation in visible and ultraviolet light-emitting diodes (LEDs), blue/violet laser diodes, and high-power electronic devices. While all of these applications are usually growth on c-plane sapphire, c-axis-oriented optoelectronic devices in particular suffer from undesirable spontaneous and piezoelectric polarization effects. Charge separation within quantum wells by polarization effects will decreases the electron-hole recombination efficiency and redshifts the emission wavelength. So much nonpolar GaN researches were did in recent years. This project will build the nonpolar GaN epitaxy and opto-electric characterization research capability. We will run this program with three years. At the first year, we will growth the GaN thin film on r-plane sapphire, a-plane SiC and c-plane sapphire at the same time by MOCVD to discuss the difference between them. We will reduce the threading dislocation and stacking faults by ELOG, nano-mask and AAO methods at the second year. Finally we will study the defect property by DLTS and growth the nonplar GaN thick film by HVPE.