标题: | 氮化镓垂直面射型雷射之电流与光学局限研究 Study on current and optical confinement of nitride-based VCSELs |
作者: | 何宗霖 Ho, Tsung-Lin 卢廷昌 Lu, Tien-Chang 显示科技研究所 |
关键字: | 垂直共振腔面射型雷射;透明导电层;Vertical-cavity surface-emitting lasers;Indium Tin Oxide |
公开日期: | 2012 |
摘要: | 本篇论文旨在探讨混合式布拉格反射镜氮化镓微共振腔结构发光元件的电、光特性。藉由数值分析方法模拟两种型式电流局限孔径(平面透明导电层以及埋藏式氮化铝结构),我们发现过去成长氮化矽在在p 型氮化镓上做绝缘层的方法(平面透明导电层结构)会影响载子注入效率,使得电流分布轻微聚集于孔径周围,增益分布远离于腔体中央造成多模操作的问题;除此之外,缺乏侧向光学局限造成模态无法集中,阈值电流也因此偏高。埋藏式氮化铝结构藉由在p 型氮化镓中驻波波腹位置成长氮化铝,做为微共振腔结构具有光学局限能力的电流阻挡层,但是为了增加电极接触面积、载子注入效率和减少光学损耗而移除透明导电层却造成严重载子聚集和漏电流问题。为了解决上述问题,本篇研究提出第三种混和氮化铝层和透明导电层的结构希望能同时达成电流以及光学局限:相较于原来平面透明导电层结构能改善载子注入效率,增益区域集中于共振腔中心有利于单模操作。除此之外,埋藏式氮化铝层提供的光学局限的特性使得模态更集中,阈值电流也因此大幅下降。同时我们保留透明导电层减少电流以及热累积的问题。透过与传统结构做比较,我们发现在同样电流注入下混和氮化铝层和透明导电层结构的元件阈值及光输出强度都有更佳的表现;串联电阻也因为透明导电层接触面积增加而有明显优化的趋势。确实证明了此种设计制作的可行性,我们化依照元件改良以及最佳化的方向逐步制作出低阈值单模操作电激发氮化镓面射型雷射。 We report on the numerical analysis of the electrical and optical properties of current-injected III-N based vertical-cavity surface-emitting lasers (VCSELs) with three types of current confinement schemes, conventional planar-Indium Tin Oxide (ITO) type, AlN-buried type without ITO, and hybrid type. The proposed hybrid structure, combined an ITO layer and a buried AlN aperture, exhibits not only a uniform and a central-concentrated current distribution but also an enhanced lateral optical confinement. Thus, the hybrid type design shows a remarkably better performance including lower threshold current and series resistance compared with planar-ITO type and AlN-buried type. The strong index guiding will induce multi-transverse mode lasing, so we also optimize the structure for single transverse mode operation. Such design provides a powerful solution for high performance III-N based VCSELs and is also viable using current state of art processing techniques. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT079815531 http://hdl.handle.net/11536/72420 |
显示于类别: | Thesis |