SiC为衬底制备InGaN绿光激光器及其关键科学问题研究

The fully semiconductor based trichromatic light source, to which a reliable solution is the combination of the InGaN based blue, green light LD and the already commercialized red light LD, has promising application prospects and wide market in the field of laser displaying. However, the InGaN based green light LD has seen a slow development, that the InGaN based green light LD was not achieved until 2009, long after the year 1996 when the InGaN based blue light LD was successfully made. The main reasons are as follows: Firstly, the InGaN green light LD needs In rich active layer, which is very difficult for InGaN epitaxy growth; Secondly, the quantum efficiency of In rich active layer based quantum well is strongly affected by the polarization effect; Thirdly, the In rich active layer based quantum well structure is easily damaged by stress exerted by afterward grown p-InGaN layer, which needs high temperature growth condition; Fourthly, the lattice mismatch between GaN and Sapphire substrate is as large as 16%. In order to conquer those problems mentioned above, this project is about to use SiC substrate, which has small lattice mismatch referring to GaN epi-layer, to prepare InGaN based cleavage cavity green light LD with a upside-down placed n-p junction. If project fully succeeded, our nation would have self-developed hi-tech patent in the field of InGaN based purple, blue, green light laser device. The outcome of this project would greatly benefit the country both economically and socially.

InGaN基蓝色和绿色半导体激光器，与现有的红色半导体激光器一起构成全半导体化的三基色光源，在激光显示等领域有巨大应用和市场。可是，InGaN绿光激光器发展缓慢，主要原因是，其有源区In组分增加，材料生长困难增大，极化效应对量子阱发光效率不利影响变大，后续p型外延层的高温生长也容易破坏有源区量子阱结构，加之Al2O3衬底与GaN有16%的晶格失配。所以1996年以Al2O3为衬底研制成功了InGaN基蓝、紫光激光器，而绿光激光器却没能成功，直到2009年才以GaN单晶为衬底研制成功。我国至今还没有见到有InGaN绿色激光器实现激射的报道。为克服上述困难，本项目提出采用和GaN晶格匹配较好的SiC为衬底，研制解理腔InGaN绿光激光器，并创新提出p-n结倒置结构。如能成功，将使我国InGaN基紫、蓝、绿光激光器研究领域形成有核心专利的自主知识产权，将产生重大的经济和社会效益。

InGaN基蓝色和绿色半导体激光器，与现有的红色半导体激光器一起构成全半导体化的三基色光源，在激光显示等领域有巨大应用和市场。    .我们针对目前InGaN基绿色激光器研制存在的科学和技术问题，按照申请书规定的研究内容进行了以下四个方面的研究：.1) 对在蓝宝石和SiC衬底上生长的GaN外延层和InGaN/GaN量子阱材料的质量提高进行了研究，通过外延方法的改进和优化，获得了高质量GaN和InGaN/GaN量子阱外延层。.2)对GaN材料系量子阱结构中应力和极化效应及其调控进行了研究，在蓝宝石和SiC衬底上进行高质量氮极性GaN薄膜外延生长和极化效应对发光管发光特性的影响研究。.3) 对GaN薄膜上低维ZnO纳米结构可控生长和准回音壁模式ZnO基激光器进行研究。.4)对n-SiC衬底垂直结构镓极性和氮极性的InGaN基绿光LED进行了研制，对以氧化镍为空穴注入层的InGaN基绿光激光器进行了研制。 .重要结果：通过外延方法改进，在蓝宝石和SiC衬底上生长出高质量GaN外延层和高质量InGaN/GaN量子阱材料。对GaN薄膜的p型掺杂进行了优化研究，极化诱导掺杂方法得到空穴浓度高达1×E+18cm-3，电阻率低至0.8Ω•cm的p型GaN系外延薄膜。在蓝宝石和SiC衬底上外延生长出高质量氮极性GaN薄膜，XRD测试(0002)和(10-12)摇摆曲线半峰宽最小可达91 arcsec和170 arcsec；制备了两种不同级性的ZnO/GaN组合LED，并对其发光特性进行了对比研究，对极化效应有了进一步了解。采用光辅助MOCVD技术实现了GaN薄膜上低维ZnO纳米结构可控生长。制备出空穴浓度高达E+19/cm3的p型NiO薄膜材料。研制出基于纳米墙网络结构准回音壁模式ZnO基激光器，可高温430 K连续激射。研制出SiC衬底垂直结构氮极性GaN基绿光LED；研制出SiC衬底解理腔垂直结构GaN基激光器，实现了415nm的光泵浦激射；研制出以氧化镍为空穴注入层的GaN基绿光激光器，实现了激射波长500nm左右的电注入室温连续绿光激光发射。许多成果在国内外是首次实现，对推动我国宽带半导体器件的发展有重要作用,具有重要的科学意义和社会效益。