氮化銦鎵/氮化鋁銦量子井在拉伸應變下各向異性光極化特性之數值模擬分析

Abstract

在本篇論文中，我們探討了極性'c'平面氮化銦鎵/氮化鋁銦量子井在拉伸應變下的發光及極化特性。並深入討論不同合金含量、井寬以及注入載子濃度的影響。 我們利用了帕松、薛丁格方程以及k·p法來求解量子井中的位能以及電子電洞在量子井中的分佈，並且採用疊代的方法來求出這些方程在此系統中的解，進而求得此系統量子井的自發性輻射、發光極化率、及光增益。我們發現此系統之量子井在拉伸應變下，激發光有極化特性並且為橫磁極化光。經由計算模擬結果我們也發現，量子井在受到拉伸應變以及位障中特定的鋁濃度下，因為材料接面處的等效極化電荷趨近為零，所以可以有效抑制史坦克效應並且增加電子和電洞波函數復合的機率來提升發光效率。研究中更進一步發現相較於ㄧ般氮化銦鎵/氮化鎵量子井，在拉伸應變之氮化銦鎵/氮化鋁銦量子井中的光增益大量提升且有較低的臨界載子密度。我們的研究指出拉伸應變之氮化銦鎵/氮化鋁銦量子井具有潛力應用在奈米柱光子晶體結構的橫磁模態邊射型雷射。

In this thesis, we study the optical characteristics and polarization anisotropy of the tensile strained polar c-plane InGaN/AlInN quantum wells with zero internal polarization field. The influence of different alloy compositions of the quantum well and barrier, quantum well widths, and injection carrier densities are discussed in detail. The developed self-consistent Poisson and 6x6 k·p Schrodinger solver has been use for studying the band structure and light emitting characteristics. We find that if the quantum well is under the tensile strain, the |Z>-like state will be lifted up, the topmost subband of valence band is dominated by the |Z> state. Therefore, the emitted light will be mainly z-polarized (TM mode). In addition, with a particular aluminum composition of the AlInN alloy as the barrier for the tensile strained InGaN quantum well, it is possible to reduce quantum-confined Stark effect and improve the spontaneous emission rate. Our results show that the tensile strained InGaN quantum well on AlInN barrier has much larger optical gain and lower threshold carrier density compared to the conventional InGaN/GaN system. The tensile strained InGaN/AlInN quantum wells have a potential to be the TM mode light source for edge emitting laser diodes with the photonic crystal cavity made by nanorod arrays.