M面氧化鋅/氧化鎂鋅多重量子井結構之光學非均向性研究

Abstract

本論文主要研究非極性的氧化鋅/氧化鎂鋅多重量子井結構的成長以及其光學特性。利用脈衝雷射濺鍍法成長量子井結構於M面的藍寶石基板上，來兩階段成長的氧化鎂鋅緩衝層使得M面多重量子井結構具有更好的晶向及更平整的表面。在螢光頻譜中，由於基板以及異質結構的應力產生高密度的晶格堆疊缺陷，量子井的發光除了有近能隙邊緣發光之外，還有另一個被推疊缺陷所束縛的發光。我們分析了樣品的激子與聲子的交互作用以及激子的束縛能，也與我們實驗室先前之成果做比較，結果顯示出量子侷限效應在光學特性上扮演了重要的部分。除此之外，我們使用了不同的分析法去驗證我們的樣品中並沒有內建電場的存在。最後，我們討論了非極性M 面多重量子井結構之光學非均向性。

This thesis report the experimental study of nonpolar ZnO/Zn1-xMgxO multiple quantum wells (MQWs) on m-plane sapphire by pulsed laser deposition. The nonpolar x = 0.2 MQWs were fabricated on the 10% m-MZO buffer by two-step growth, which effectively reduces the extra domain and surface roughness but produces high basal-plane stacking faults (BSF) density. The photoluminescence (PL) spectra show a blueshift near-band edge (NBE) emission and strong stacking faults, coming from both substrate and heterostructure, optical emissions of MQWs. We also investigated the exciton – LO phonon coupling and the exction binding energy for each sample and compared that with the previous x = 0.1 MQWs results of our group. The results indicate the quantum confinement effect play a dominant role. Additionally, we used various analyses to identify that there have no internal electric in our samples. Finally, we discuss the optical anisotropy properties of our non-polar m-plane MQWs with x = 0.2.