GaN基激光器在激光显示和激光照明等领域具有广阔的市场应用前景。目前自支撑GaN衬底价格昂贵，同质外延的激光器制造成本较高。采用Si衬底制作激光器，有望将成本降低2-3个数量级。但是由于GaN与Si衬底之间存在大的晶格失配、热膨胀系数失配和激光器AlGaN光场限制层应力，GaN基激光器中应力大、缺陷密度高，严重影响Si衬底激光器的性能和寿命。本项目拟在已有Si衬底紫光激光器研究基础上，围绕Si衬底蓝光激光器这一大失配、强极化体系中的应力调控和缺陷控制开展工作，研究应力与缺陷之间的相互作用。本项目创新提出了一种基于侧向外延技术的新型激光器结构，采用SiO2/SiNx反射性复合结构作为侧向外延的介质掩膜，不仅可降低穿透位错密度2-3个数量级，还可取代传统AlGaN光场限制层。该新型激光器中的应力小、缺陷密度低、光场限制好、串联电阻小，有望大幅提升Si衬底GaN基激光器的性能和寿命。

GaN-based laser diodes (LDs) have been widely used in the field of laser display and laser illumination. Now the price of free-standing GaN substrates is quite expensive, which makes the fabrication cost of GaN-based LDs quite high. By using Si substrates, the cost could be reduced by 2-3 orders. However, a high density of defects and crack network exists in GaN-on-Si LDs due to large mismatch in lattice constant and thermal expansion between GaN and Si, which affects the performance and lifetime of GaN-on-Si LDs seriously. This proposal will focus on stress regulation and defect control of GaN-on-Si blue LDs based on existing GaN-on-Si violet LDs, the mutual relationship between stress and defects will be also studied. This proposal will also propose a new LD structure based on epitaxial lateral overgrowth innovatively. The SiO2/SiNx dielectric mask with composite structure not only can reduce the threading dislocations by 2-3 orders but replace traditional AlGaN cladding layer. Compared with conventional LDs, LDs with this structure have many advantages, such as less stress, lower defect density, better optical confinement and smaller resistance, which are expected to improve the performance and lifetime of GaN-on-Si blue LDs.