高质量立方氮化硼薄膜的异质外延及其p-i-n结构日盲紫外光电探测器研究

Cubic boron nitride (cBN) is III-V wide-band-gap semiconductor with the widest band gap. It is the ideal material system for emerging solid-state deep-ultraviolet (DUV) photodetectors, specially operating in solar-blind region UV. This is because of their potential application in flame monitoring and detection, biomedicine, environmental monitoring and UV astronomy, etc. In addition, cBN based UV detectors have the advantage of being solid-state and of small size, with excellent chemical and thermal stability, thereby saving energy and having a long lifetime. To date, however, the achievement of cBN based UV detectors has been severely hindered by the high defect density and extremely inefficient doping. In this project, we will bundle the know-how about two different wide-band gap materials into a joined effort in order to synthesize hybrid structure with new functional properties. By combining the growth dynamics with the state-of-the-art deposition and characterization tools, the growth processing and defect will be monitored in order to achieve phase-pure, impurity-free, high-quality cBN films of electronic grade on top of diamond substrate. This should allow, in a second step, to design a high-performance solid-blind DUV photodetector based on p-diamond/i-diamond(i-cBN)/n-cBN hybrid structure. In the end, by fabricating metallic nanoparticles on this p-i-n structure, the device performance will be greatly improved due to the localized surface plasmon effect. This project will support the improvement and practical application of cBN based UV optoelectronic devices.

立方氮化硼(cBN)是禁带最宽的III-V族半导体材料，具有击穿场强高、热导率大、耐高温、抗辐照等特点，是在极端条件下工作的日盲紫外探测器的首选材料。目前合成的cBN薄膜材料中存在缺陷密度高、掺杂效率低等问题，加上器件结构设计受限，严重制约其在紫外光电探测和其他电子领域的应用。本项目拟制备p-金刚石/i-金刚石(或i-cBN)/n-cBN的p-i-n异质结构，运用外延生长动力学因素进行生长模式和界面调控，在生长过程中抑制缺陷的产生，采用超晶格掺杂调控、协同共掺杂等新型技术，提高掺杂效率，研制cBN基p-i-n日盲紫外光电探测器，结合金属纳米颗粒的局域表面等离激元进一步提升器件性能。本项目的实施旨在突破低缺陷密度、高效掺杂的cBN外延薄膜材料制备困难这一技术瓶颈，为发展高性能cBN基日盲紫外光电探测器提供新型结构设计方案，有望对传统材料向高端电子材料转型起到积极的推动作用。

立方氮化硼(c-BN)是典型的宽禁带半导体之一，在高温、高频、大功率电子器件以及现代汽车、航空航天等方面均有着巨大的应用潜力。其带宽可达6.4 eV，对应的截止波长193 nm，无需配置滤波系统、更不需制冷，是制作日盲紫外探测器的首选材料。在国家自然科学基金项目的支持下，在BN的生长动力学、外延生长工艺、高效掺杂和深紫外光电探测器应用方面开展了深入研究，取得了以下结果：1）采用离子束溅射手段，在无金属催化衬底和过渡层的情况下，在介质衬底上直接获得2英寸大面积平整均匀的h-BN膜，厚度为50到500nm，基于该类薄膜的日盲深紫外光电探测原型器件展现了在深紫外日盲区极佳的光电响应信号，响应峰值在0.5AW-1@205nm，探测率为6.92×109Jones和优异的开关比103。2）实验上获得了磁控溅射手段制备高质量单晶c-BN薄膜的外延生长的最佳工艺条件，构筑异质界面，及通过界面调控载流子输运，获得了优异的室温整流特性。3）理论上应用分子动力学与蒙特卡罗方法在原子水平上理解了团簇与表面的相互作用，获得了金刚石/c-BN异质结构的界面性质。4）通过构建外延生长的特定化学环境，获得了低缺陷密度和超宽禁带的BN薄膜。5）在此基础上采用协同共掺杂、原位碳掺杂等手段获得了高掺杂效率的n型BN膜，制备了BN基pn结，研制了基于本征BN膜、掺杂型BN厚膜、和局域表面等离激元增强型日盲紫外原型探测器件。本项目的实施为发展高性能c-BN基日盲紫外光电探测器提供新型结构设计方案，有望对传统材料向高端电子材料转型起到积极的推动作用。.基于本项目的研究成果，共发表了学术论文12篇，获国家发明专利7项。在项目开展期间，培养硕士研究生5名，其中2人获得校优秀硕士学位论文，1人获校求实奖学金，1人获国家奖学金。