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(MOVPE)技术在长波长发光二极管和激光器的半极性GaN表面上外延生长GaN基材料的过程。限制传统c-面GaN光电子器件性能的主要问题之一是异质界面(如InGaN-GaN，AlGaNGaN)产生的强烈极化效应。在偏向于c平面的半极表面上生长将允许极化场的显著减小。在项目的第二阶段，将研究在低缺陷密度的半极体GaN衬底上生长In-AlGaN异质结。基于以前的结果，我们将重点研究具有(1122)和(2021)取向的GaN，因为它们提供了优异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。这包括对欧姆接触的研究，以及进一步改进切割和干法蚀刻技术以制造激光反射镜。最后，我们将制作和表征LED、光泵浦激光异质结和电流注入激光二极管。此外，我们还将探索InGaN量子阱LED和半极GaN上激光器的基本物理性质，如复合动力学、偏振场的量化、半极LED出射光的偏振态以及半极波导的偏振特性。

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.