氮化銦鎵量子井的光激發螢光之研究

Abstract

在這個論文研究中，我們首先討論了不同的載子複合機制。藉由這些機制的研讀，我們提出一個從光激發螢光(PL)頻譜得到量子井的IQE的方式。並且透過IQE的比較，我們能夠將主動層的成長條件和結構參數最佳化。藉由假設在77K的光激發量子效率的最大值歸一化，在發光波長在430nm和510nm的試片中，我們可以分別達到66%和31%的IQE。同時，我們發現Shockley-Read-Hall非輻射性複合是限制主動層IQE的最重要的載子復合機制。另外，在這篇研究中，我們也提出一些在InGaN多層量子點上所觀察到的特殊現象，例如 特殊的光激發量子效率曲線、InGaN量子井對於特定密度下的線/穿透差排(threading dislocation)的不敏感、PL頻譜隨光激發功率增加的藍移現象。

In this thesis research, we first studied different carrier recombination mechanisms, and then propose an approach to obtain internal quantum efficiency (IQE) from photoluminescence (PL) experiments. Through comparing IQE, the growth condition and structural structure of InGaN/GaN multi-quantum well (MQW) have been optimized. IQE of 66% at 430nm and 31% at 510nm were measured respectively by assuming maximum PL quantum efficiency at 77K is 100%. Shockley- Read-Hall nonradiative recombination is found to be the most critical mechanism limiting IQE. Other unique phenomena of InGaN/GaN MQW induced by piezoelectric polarization and indium compositional fluctuation will also be presented, i.e. the droop of PL quantum efficiency at low temperature and carrier concentration, the insensitivity of IQE to threading dislocation at certain density range, blue shift of transition peak.