二維量子井半導體雷射模擬

Abstract

本文最主要的目的是將描述二維量子井半導體雷射物理的光和電特性的模 式整合為一體, 以全面性的觀點來模擬在穩態時的電和光特性. 所包含的 物理模式有波松 (Poisson) 方程式, 電流連續方程式, 馬克斯威爾 (Maxwell) 電磁波方程式以及光子數目的增益方程式. 為了準確的描述量 子井中光增益和載子波函數, 濃度以及雷射頻率的關係, 薛丁格 (Schro- dinger) 方程式也包含在我們的模擬中. 整個的模擬是建立在自 我一致 ( self-consistent) 的架構上. 從模擬中可獲得量子井雷射的能 帶圖 (band diagram), 電子電洞分佈, 雷射光頻率, 光的分佈, 電流和 雷射光強度的關係曲線, 雷射的臨界電流等等.我們將此模擬運用在 graded-index-separate-confinement-hetero- junction buried quantum-well (GRINSCH buried-QW) 雷射, 並和實驗值做比較而獲得良 好的吻合. 我們並研究一些在相同結構上改變長度對雷射臨界電流的影 響, 而發現了 GRINSCH 寬度約在 0.2 微米 (um) 時, 量子井寬度約在 120 埃時, 能獲致最低的臨界電流, 我們也做了良好的物理解釋. We develop a two-dimensional simulation for quantum well (QW) lasers. The simulation model includes the Poisson equation, continuity equations, Maxwell equation and photon rate equation. The carrier concentrations and the optical gain in the quantum well are evaluated from the Schrodinger equation. The result of the simulation is the laser output power, threshold current, optical field and carrier concentration distributions. In addition,the subband energies in the conductionband and in the valence band, the overlap integral for optical transitions and the lasing frequency are all derived from the simulation. We have applied our model to the graded-index-separate confinement-heterojunction buried-quantum- well (GRINSCH uried-QW) lasers. Good agreement of the output power-currentharacteristics between the experimental and simulation resultss obtained. We also evaluate the dependence of the laserharacteristics in the structure parameters. The best opticalonfinement can be achieved for a GRINSCH width of 0.2 um. Inddition, the lowest threshold current at a quantum- well widthf 120 A is abtained.