Vertical Cavity Blue and Ultraviolet Light Emitters

0070887 Nurmikko在这个项目中，Nurmikko，他的研究生和合作者的目标是研究，设计和开发光电器件和光学物理概念，这将导致实现蓝色和紫外垂直腔光发射器，基于宽带隙氮化物半导体异质结构。 特别是，三年计划的具体目标是（a）谐振腔发光二极管（RCLED）和（B）垂直腔面发射激光器（VCSEL）的演示和制造。 虽然紧密相连，这些新的，紧凑的短波长器件的发展所面临的技术挑战可以逻辑上分为两大领域：（i）的方法和实施的光学微谐振器结构和（ii）的设计和实现的pn结为基础的注入器结构。 为了实现InGaN和AlGaN异质结构的高Q因子垂直腔，Nurmikko及其同事的目标是创建加工技术，该技术将创建达到1000-2000范围内的Q因子的光学结构，以降低激光阈值要求。 该方法是基于单片集成的两个电介质DBR，也专注于“混合”结构与一个电介质和一个生长DBR。 VCSEL结构的光学增益谱的研究形成了另一个关键项目领域，以详细说明InGaN和AlGaN有源介质的增益谱，以优化低阈值VCSEL。 Nurmikko及其同事将研究基础微腔物理学，以增强InGaN和AlGaN VCSEL和RCLEDS的光发射。 激子对振荡器强度的增强可以集中光学增益，从而显著降低氮化物VCSEL阈值。 同样，RCLED的自发发射特性预计将大大增强。为了实现二极管垂直腔发射器，Nurmikko及其同事将在两种类型的实验中研究横向p注入：（i）使用近场成像技术研究横向扩散，以及（ii）LED微结构的设计，其中电流扩散可以从电致发光空间成像中获得。 对于蓝色和NUV VCSEL工作，他们还将专注于p-GaN/AlGaN调制掺杂异质结构的结合，以增强p侧导电性。 他们将解决的具体特征之一涉及电子结构的定制，以便可以减少界面散射（因此提高空穴迁移率）。 他们建议使用非常大的内置压电和自发电介质极化效应来静电设计异质结限制分布。 他们还将研究使用外延横向过生长（ORG），以促进“掩埋”DBR反射镜的结合，以及定义电流孔，用于将空穴传输到有源器件区域（由垂直谐振器定义）。正在进行的研究的一个具体特点是与惠普公司的密切合作（惠普实验室和光电部门，现在更名为安捷伦科技），以及桑迪亚国家实验室。 这种工业/政府实验室连接将是项目工作的一个组成部分。

0070887NurmikkoIn this project, Nurmikko, his graduate students, and collaborators aim to study, design, and develop optoelectronic device and optical physics concepts that will lead to the realization of blue and ultraviolet vertical cavity light emitters, based on wide band gap nitride semiconductor heterostructures. In particular, the specific goals of the three year program are the demonstration and fabrication of (a) a resonant cavity light emitting diode (RCLED), and (b) a vertical cavity surface emitting laser (VCSEL). Although closely interconnected, the technical challenges facing the development of these new, compact short wavelength devices can be logistically grouped into into two broad areas: (i) the approach and implementation of the optical microresonator structure and (ii) the design and realization of a pn-junction based injector structure. To achieve high Q-factor vertical cavities for InGaN and AlGaN heterostructures, Nurmikko and co-workers aim is to create processing techniques that will create optical structures reaching Q-factors in the 1000-2000 range for reducing the laser threshold requirements. The approach is based on monolithic integration of two dielectric DBRs and also focus on "hybrid" structures with one dielectric and one as-grown DBR. Study of the optical gain spectra of the VCSEL structures forms another key project area, to detail the gain spectra of the InGaN and AlGaN active media for optimizing these for low threshold VCSELS. Nurmikko and co-workers will study fundamental microcavity physics to enhance light emission from InGaN and AlGaN VCSELs and RCLEDS. Excitonic enhancement to oscillator strength can concentrate optical gain so as to significantly reduce a nitride VCSEL threshold. Similarly, spontaneous emission properties for an RCLED are expected to be dramatically enhanced.For achieving a diode vertical cavity emitter, Nurmikko and co-workers will study lateral p-injection in two types of experiments: (i) the use of near field imaging techniques to study lateral diffusion, and (ii) the design of LED microstructures where current spreading can be obtained from electroluminescence spatial imaging. For the blue and NUV VCSEL work they will also concentrate on the incorporation of p-GaN/AlGaN modulation doped heterostructures for enhancing the p-side conductivity. One of the specific features that they will address concerns the tailoring of the electronic structure so that interface scattering can be reduced (hence the hole mobility enhanced). They propose to use the very large built-in piezoelectric and spontaneous dielectric polarization effects to electrostatically design the heterojunction confinement profile. They will also study the use of epitaxial lateral overgrowth (ELOG) to facilitate both the incorporation of "buried" DBR mirrors as well as to define current apertures for channeling hole transport to the active device region (as defined by the vertical resonator).A specific characteristic of the ongoing research is a close collaboration with Hewlett-Packard (both HP Labs and the Optoelectronic Division, now renamed Agilent Technologies), as well as Sandia National Laboratories. This industry/government laboratory connection will be an integral part of the project work.***