AlGaN日盲紫外单光子雪崩探测器关键技术研究

Facing technical bottlenecks of developing the solar-blind single-photon detection technique based on AlGaN semiconductors, we will carry out the researches on growth mechanisms and kinetics of high-Al-composition AlGaN lateral epitaxial overgrown, stress-defect evolution, dislocation generation and annihilation mechanisms, and self-compensation behavior of p-type doping and control methods of Mg acceptor activation energy in order to overcome the difficulties in fabricating the low-dislocation-density AlGaN materials and in realizing high-conductivity p-type doping. The effects of heterostructure polarization, energy-band lineup and dislocation scattering on carrier impact ionization are investigated and their relations are also established. The precise control of electric field distribution on the multiplication region by fine doping will be developed, and the carrier transport and leakage models under high electric field are studied by analyzing the tunneling and avalanche mechanisms. The key device processes including low-damage etching, field plane, and surface passivation are developed together with innovating device design and the state-of-the-art AlGaN material growth in order to break through the solar-blind single-photon detection technique.

本项目主要针对AlGaN本征日盲紫外单光子雪崩探测器所面临的关键科学问题和技术瓶颈，重点开展基于AlN和AlGaN图形模板的高Al组分AlGaN材料的横向外延生长机理和动力学行为、应力-缺陷演变过程和位错的产生与湮灭机制以及p型掺杂的自补偿行为、Mg受主有效调制掺杂与基于价带结构的离化能研究，突破低缺陷密度AlGaN材料制备技术和高电导p-AlGaN材料的有效掺杂技术；深入研究异质结极化和能带工程对载流子碰撞电离的影响机制和协同调控规律，建立考虑了极化与缺陷散射的氮化物半导体载流子碰撞电离模型；开展精细掺杂对倍增层电场分布的精准调控研究，揭示高场下载流子隧穿效应与雪崩效应竞争机制，建立高场下载流子输运与漏电流物理模型；发展低损伤刻蚀、场板、表面钝化等器件关键工艺，解决器件制备中的技术难题。通过创新雪崩光电探测器设计理论，攻克材料与器件制备关键技术，实现日盲紫外单光子探测技术的突破。

项目围绕AlGaN日盲紫外单光子雪崩探测器中存在的重要科学问题和核心关键技术开展了系统研究。创新发展了基于自组装纳米图形衬底的AlGaN横向外延技术，将高Al组份AlGaN位错密度降低近两个量级至2E7/cm2；发现AlGaN材料p型掺杂的界面效应，并提出一种基于Mg受主脉冲掺杂的界面Ga修饰技术，通过降低Mg受主激活能，大幅提升了p型掺杂效率，得到了空穴浓度高达8.3E18 cm-3的p-Al0.42Ga0.58N材料，相应电阻率为 0.51 Ωꞏcm，空穴浓度与电阻率特性均处于当前国际研究领域的领先水平；基于极化和能带工程，首次提出一种异质结离化增强型AlGaN雪崩光电探测器结构，所制备的离化增强型探测器增益达到7.4E5，雪崩点暗电流控制在pA量级，为目前高Al组份AlGaN雪崩探测器国际公开报导最好值；基于不同类型位错的研究，结合实验和第一性原理计算，揭示了AlGaN雪崩光电探测器高场下暗电流机制与预击穿机理，并建立了相应的隧穿模型；创新发展了基于AlGaN/GaN异质结光电晶体管的雪崩光电探测器，同时发挥异质结光电晶体管的光诱导增益与雪崩光电二极管的载流子碰撞电离雪崩倍增的作用，在53.5 V的低偏压下获得3.6E4的高增益。成功开发了AlGaN小角度斜台面终端工艺和光电化学刻蚀损伤修复工艺，改善了器件边缘电场的分布，降低了器件边缘提前击穿的风险，重要提升了器件的成品率和可靠性。.在国内外重要学术刊物上共发表SCI收录文章56篇；申请发明专利14项，PCT4项，其中11项获得授权；获得中国产学研合作创新成果一等奖1项、中国发明协会发明创新创业一等奖1项。国内国际学术会议大会报告/特邀报告10次，并获国际大会最佳年青科学家奖1次；培养博士生4人，硕士生13人；项目组成员1人入选江苏省“333高层次人次培养工程”第二层次中青年领军人才计划。