基于Mg受主能级耦合途径的AlGaN高效p型掺杂研究

High-Al-content AlGaN (greater than 40%) is the irreplaceable semiconductor system for deep ultraviolet light-emitting devices and detectors, and high-efficiency p-doping for high-Al-content AlGaN is the key aspect and one of the core contents for high-performance ultraviolet optoelectronic devices. Aiming at realizing effective activation for Mg dopants in AlGaN and obtaining p-type AlGaN epitaxial films with high conductivity, this requested item adopts enhanced coupling ways for Mg acceptor levels to effectively decrease activation energy as the main technical routes, using some innovative methods, including the enhanced mutual coupling of Mg acceptor levels via lateral epitaxial growth, δ-doping in the barriers combined with enhanced coupling via resonance between Mg acceptor levels with the miniband in short-period superlattice structures, and enhanced coupling via resonance between Mg impurity levels and valence-band maximum in AlGaN films with periodic oscillation of Al content realized by epitaxial growth. Based on these methods, p-doping for high Al-content AlGaN films will be systematically studied to obtain p-type high-Al-content AlGaN films with hole concentration greater than 1x10^18cm^-3, as well as to provide solutions for AlGaN-based high-performance ultraviolet optoelectronic devices. In the recent years, the research group involving the item applicants has been engaged in growth of III-nitide semiconductors and low-dimensional quantum structures as well as study of the physical properties, and has established very good working foundation and experimental conditions. The contents of this requested item are at the reseach forefront of III-nitide semiconductors.

高Al组分AlGaN（Al组分大于40%）是制备深紫外发光和探测器件不可替代的半导体体系，其高效p型掺杂是制备高性能器件的关键环节和核心内容之一。本申请项目以实现AlGaN中Mg掺杂原子的有效激活及高导电率p型AlGaN为目标，以Mg受主能级的耦合增强导致有效激活能下降为主要技术途径，拟采用侧向外延增强Mg受主能级相互耦合、垒区δ掺杂结合超晶格微带与Mg受主能级共振增强耦合以及外延生长中Al组分周期性振荡增强Mg受主能级与AlGaN价带顶耦合等创新方法，系统开展AlGaN的p型掺杂机理研究，制备出空穴浓度超过1x10^18cm^-3的高Al组分 AlGaN外延薄膜，为AlGaN基高性能紫外光电器件的研制提供解决方案。本项目申请人及所在课题组近年来主要从事氮化物半导体及其低维量子结构的外延生长和物性研究，具备良好的工作基础和条件。本项目研究内容处于当前国际上氮化物半导体研究的前沿领域。

高Al组分AlGaN（Al组分大于40%）是制备深紫外发光和探测器件不可替代的半导体材料体系，其高效p型掺杂是制备高性能紫外光电器件的关键和核心内容之一。本申请项目以实现AlGaN中Mg掺杂原子的有效激活及高导电率p型AlGaN为目标，开展AlGaN的p型掺杂机理研究。项目执行4年来共发表学术论文13篇(包括封面论文1篇，研究亮点2篇，Semiconductor Today网站报道1篇)，申请/获得国家发明专利4件，在国内学术会议上做邀请报告报告4次，毕业博士研究生4人，硕士研究生1人。取得的代表性研究成果如下：.（1）通过生长热力学条件优化，实现了厚度小于1nm的AlGaN的MOCVD外延生长。利用该技术制备了超短周期超晶格结构的p-AlGaN，其阱厚为1.8nm，垒的厚度仅为0.9nm，阱的组分为0.37，垒的组分为0.67，平均组分高达0.49。同时该结构也实现了1×10^19cm^-3的Mg掺杂浓度，霍尔测试其室温下空穴浓度稳定大于3.0×10^18cm^-3。进一步优化后Al组分0.52的AlGaN，室温下空穴浓度高于6.0×10^18cm^-3。.（2）开展了p-AlGaN超短周期超晶格的电学和光学特性研究，基于该p-AlGaN的深紫外LED器件反向漏电达到10-8 A•cm^-2量级，而串联电阻随着超晶格周期的增加而变小，呈现出微带输运特点，并显示了在大电流下的较大潜力。通过光学测试发现，该p-AlGaN紫外波段（274-400纳米）透过率高（大于90%），能为深紫外发光器件光提取提供大的剪裁空间。