雷射濺鍍法成長非極性氧化鋅/氧化鎂鋅之量子井結構於M面藍寶石基板及其光學特性研究

Abstract

本論文主要研究非極性的氧化鋅/氧化鎂鋅的量子井結構的成長與光電性質，利用雷射濺鍍法成長此量子結構於M面的藍寶石基板上。使用二階段成長法的氧化鋅來當作緩衝層，我們獲得更好的晶向、以及更平整的成長表面。在螢光光譜上，來自量子井中的發光，不僅有近能隙邊緣發光還有另一個受基面堆疊缺陷束縛的高強度放射光都有藍移的現象發生。我們透過分析了激子與聲子的交互作用與激子的結合能，了解量子侷限在樣品中扮演了重要的部分。除此之外，全部的樣品其近能隙邊緣發光，能量都高過於氧化鋅塊材的3.36電子伏特，並且對應於無內建電場效應的理論曲線上，而改變激發能量的螢光分析中也發現發光不產生藍移。各個現象都表示了我們成功M面成長了非極性結構，且不僅具有量子侷限的效應，還避免了量子史塔克效應的作用。

This thesis report the experimental study of nonpolar ZnO/MgZnO multiple quantum wells (MQWs) on m-plane sapphire by pulsed laser deposition. The nonpolar MQWs were fabricated on the m-ZnO buffer by two-step growth, which effectively reduces the ratio of extra domain and surface roughness but produces high basal-plane stacking faults (BSF) density. So, the photoluminescence (PL) spectra, shows not only a blueshift near-band edge (NBE) emission but strong stacking faults emissions from QWs, We also investigated exciton and LO-phonon coupling and exction binding energy for each sample, the results indicated quantum confinement effect play a dominant role. In addition, the NBE emission are all located above 3.36 eV even for the well width reaching 16 nm consist with the theoretical excitonic transition energies with no internal electric field, and the fixed peak of power-dependent LT-PL, those exhibits evidences of the absence of quantum-confined Stark effect in these samples. The fabrication of nonpolar MQW is successful and optical properties shows not only possess the quantum confinement effect but also prevent from the QCSE.