量子井中增益與吸收係數之計算以及半導體雷射中藉由多重量子位壘降低漏載子效益之評估

Abstract

首先,我們計算了在量子井雷射中沒有電子與電洞之間的庫倫作用時之光 學增益與吸收係數.當我們加入Intraband-relaxation之效應時,雖然量子 井具有像梯狀的能態密度,但是增益與吸收之光譜形狀卻變得平滑且加寬. 然而,導帶電子與價帶電洞之間的庫倫吸引力導致了在吸收邊緣附近,特別 是吸收邊緣以下,之量子井的光學性質有很大的改變.在能帶以下有強烈的 吸收譜線,也就是,激子躍遷比能帶躍遷需要較少的能量.最後,我們第一次 藉由計算載子的"阻擋效率"對任何多重量子位壘結構之最佳化設計提供了 一個清楚而且簡單的方法.我們的方法預測了一個SCH-SQW雷射在具有最佳 化多重量子位壘結構時之微分量子效率有著相當大的改善而且與實驗結果 符合. First, the optical gain and absorption without Coulomb interacti- on between electrons and holes are analyzed for quantum well las- ers. When the intraband relaxation is considered, the gain/absor- ption spectral shape becomes smooth and broad in spite of the sh- arp step-like density of state. However, the Coulomb attraction between the conduction-band electron and the valence-band hole l- eads to considerable changes in the optical properties of the qu- antum well around the absorption edge, especially below absorpti- on edge. There are intense absorption lines below the bandgap en- ergy, that is, less photon energy is required for the exciton tr- ansition compared with the bandgap transition. Finally, we have provided a clear and simple method for the optimal design of any MQB structure by calculating the carrier blocking efficiency for the first time. Our method predicted substantial improvement of the differential quantum efficiency of a SCH-SQW laser with opti- mal MQB design and agrees with experimental results.