绿光激光器InGaN量子阱有源区热退化及其抑制方法

Laser-based displays constructed by red/green/blue laser sources can offer the most saturated colors and the most large color gamut, and has attracted great interests among researchers. High-performance GaN-based green laser diodes(LDs) are desirable for laser-based displays. Thermal degradation of InGaN quantum well (QW) active region is one of limitation to improve the performances of GaN-based green laser diodes. We propose to study in details the characterization methods of thermal degradation of InGaN QWs in green LD structures and the main factors leading to the thermal degradation. Based on these studies, the mechanism of thermal degradation of In-rich InGaN QWs will be disclosed. . Relatively low growth temperature for p-AlGaN cladding layer subsequent to InGaN QWs will be used to suppress thermal degradation of InGaN QWs. However, the issue of high resistance of p-AlGaN due to low growth temperature need to addressed. Therefore, we will study defects, impurities，Mg doping and electrical properties of AlGaN:Mg grown at low temperature in order to disclose the cause of high resistance for low-temperature grown p-AlGaN layer and find out the way to reduce it. . On the other hand, adopting ITO layer as upper cladding instead of p-AlGaN in green LD structures can avoid the thermal process and thus improve the quality of InGaN QWs. Therefore, we will study the design and fabrication of green LD structure with ITO upper cladding layer in order to improve the performances of GaN-based green LDs.

红绿蓝三基色激光显示可以实现大色域、高饱和度显示，是国际显示领域的研究热点。激光显示技术迫切需要高性能的GaN基绿光激光器，InGaN量子阱的热退化是限制GaN基绿光激光器性能提升的瓶颈之一。本课题拟深入研究GaN基绿光激光器InGaN量子阱热退化的表征方法、影响因素，揭示高In组分InGaN量子阱的热退化机理。. 为了抑制绿光激光器InGaN量子阱有源区的热退化，拟采用相对低的温度生长p-AlGaN上限制层，为此需要解决低温生长p-AlGaN的高电阻问题。拟研究低温生长p-AlGaN的缺陷、杂质、Mg掺杂和电学性质，揭示其电阻高的机理，寻求降低其电阻的方法。. 另一方面，拟采用ITO为绿光激光器的上限制层，避免InGaN量子阱经受高温过程，提升绿光激光器InGaN量子阱有源区质量。 拟研究新型ITO上限制层绿光激光器的结构设计和制备，提升绿光激光器性能。

红绿蓝三基色激光显示可以实现大色域、高饱和度显示，是国际显示领域的研究热点。激光显示技术迫切需要高性能的GaN基绿光激光器，InGaN量子阱增益区的热退化是限制GaN基绿光激光器性能提升的主要瓶颈之一。. 本课题深入研究了GaN基绿光激光器InGaN量子阱热退化的影响因素，揭示了绿光量子阱增益区热退化机理，在高温作用下富In的InGaN团簇分解，形成In金属和孔洞，并提出了抑制缺陷的方法。. 为了抑制绿光激光器InGaN量子阱有源区的热退化，需要采用相对低的温度生长p-AlGaN上限制层。研究了低温生长p-AlGaN的缺陷、杂质和电学性质，揭示了C杂质是低温生长p-AlGaN:Mg的主要补偿施主，提出了抑制C杂质的生长方法，大幅降低了p-AlGaN:Mg的电阻率。. 进一步设计并制备了以ITO为p型限制层的新型激光器，大幅抑制了量子阱质量退化，绿光激光器自发辐射的内量子效率达到76%，阈值电流密度低至1.6 kA/cm2，达到国际一流水平。. 在以上工作基础上，研制出光功率达到500mW的绿光激光器。绿光激光芯片和器件已经得到国内企业的验证，是国内唯一能提供国产绿光半导体激光芯片的研制单位。在国内外著名期刊上发表论文23篇，国际国内会议邀请报告21次，申请或授权专利15个。