Study of the Emission Characteristics of InGaN/GaN and CdZnO/ZnO Quantum-well Structures with the Photoluminescence Spectroscopy

在本論文中，我們利用光致發螢光技術研究氮化銦鎵/氮化鎵發光二極體及氧化鎘鋅/氧化鋅發光二極體之光學特性。首先以氮化銦鎵半導體雷射 (波長406nm) 對氮化銦鎵/氮化鎵發光二極體進行隨溫度變化的螢光頻譜和隨激發強度變化的螢光頻譜量測，研究在高溫成長不同厚度的p型氮化鎵下，量子井因為受到高溫熱退火而重整銦聚集結構並加強載子局部效應，也因為晶格常數的不匹配而增強內部電場，造成內部量子效率及史塔克效應不同的影響。此外，用氦鎘雷射 (波長325nm) 對氧化鎘鋅/氧化鋅發光二極體進行隨溫度變化的螢光頻譜和隨激發強度變化的螢光頻譜量測，研究在氮化鎵及氧化鋅基板上成長氧化鎘鋅/氧化鋅量子井，造成內部量子效率及史塔克效應的影響，並利用兩個高斯分佈擬合發光頻譜。當量子井中鎘濃度高時，發光頻譜中存在著rock-salt氧化鎘鋅結構及wurtzite氧化鎘鋅結構，並隨著量子井中鎘濃度的增加，rock-salt結構相對wurtzite結構對全頻譜的影響更甚。In this study, we demonstrate the emission characteristics in InGaN/GaN QWs and in CdZnO/ZnO QWs with photoluminescence measurements. First, temperature-dependent photoluminescence and excitation power-dependent photoluminescence are performed on InGaN/GaN QWs with an InGaN-based diode laser (λ=406nm). The counteraction between the increased carrier localization effect in the QWs, which is caused by the thermal annealing process, and the enhanced quantum-confined Stark effect in the QWs, which is caused by the increased piezoelectric field, when the different thickness of p-type layer is grown at a high temperature on the InGaN/GaN QWs is illustrated. Next, we demonstrate the results of temperature-dependent photoluminescence and excitation power-dependent photoluminescence with a He-Cd laser (λ=325nm) to understand the emission behaviors of the CdZnO/ZnO QW on GaN and ZnO templates. With two-Gaussion fitting, wurtzite CdZnO structure and rock-salt CdZnO structure exist in the CdZnO well layers. The rock-salt structures may dominate over the wurtzite structures in photoluminescence intensity when the total Cd content is high