Polarization field control in GaInN quantum well heterostructures on semipolar growth surfaces

本项目的目的是研究利用金属有机气相外延技术（MOVPE）在半极性GaN表面上制备GaN基材料用于长波发光二极管和激光器的外延生长过程。限制传统c-平面GaN上光电器件性能的主要问题之一是发生在异质界面（例如InGaN-GaN， AlGaNGaN）上的强极化效应。生长在半极性表面上，倾斜于c平面将允许极化场的显著减少。在该项目的第二阶段，将研究在低缺陷密度半极性块状GaN衬底上生长In- algan异质结构。基于之前的结果，我们将重点研究（1122）和（2021）取向的GaN，因为它们提供了出色的铟掺杂效率和整体良好的形貌。该项目的另一个目标是开发非极性和半极性LED和激光器件的制造工艺。这包括欧姆接触的研究和进一步改进切割和干蚀刻技术来制造激光反射镜。最后，我们将制作和表征led，光泵浦激光异质结构和电流注入激光二极管。此外，我们将探索半极性GaN上的InGaN量子阱led和激光器的基本物理特性，如复合动力学、偏振场的量化、半极性led发出的光的偏振态以及半极性波导的偏振特性。

The objective of this project is to investigate the epitaxial growth process of GaN-based materials on semipolar GaN surfaces for long wavelength light emitting diodes and lasers using metal organic vapor phase epitaxy (MOVPE). One of the main problems that limits the performance of optoelectronic devices on conventional c-plane GaN are the strong polarization effects that occur at the heterointerfaces (e.g. InGaN-GaN, AlGaNGaN). Growth on semipolar surfaces inclined to the c-plane will allow a significant reduction of the polarization fields. In the second phase of the project, the growth of In-AlGaN heterostructures on low defect density semipolar bulk GaN substrates will be investigated. Based on previous results we will focus on GaN with (1122) and (2021) orientations, since they provide excellent indium incorporation efficiencies and overall good morphologies. Another goal of the project focuses on the development of fabrication processes for non- and semipolar LED and laser devices. This includes investigation of ohmic contacts and further improvement of cleaving and dry etching techniques to create laser mirrors. Finally, we will fabricate and characterize LEDs, optically pumped laser heterostructures and current-injection laser diodes. Furthermore, we will explore fundamental physical properties of InGaN quantum well LEDs and lasers on semipolar GaN, e.g. the recombination dynamics, quantification of the polarization fields, the polarization state of light emitted by semipolar LEDs, and the polarization characteristics of semipolar waveguides.