金属表面等离子体共振增强自驱动紫外光探测器性能及物理机制研究

Building the self-powered phtodetectors (PDs) without power supply is the effective method to realize the integration, miniaturization and multi-functionalization of the micro/nano sensor devices. It is the key factors of increasing the light absorption in the UV region and promoting the effective separation of photo-generated carriers to realize the high performance devices. In this project, the self-powered UV PDs are fabricated using by the ordered II-type heterojunctions with wide band-gap semiconductors. The metal nanoparticles and dielectric layer are introduced into the heterojunctions. The devices reach the collaborative optimization of the metal localized surface plasmon resonances and the interface effect of heterojunctions by controlling the metal nanoparticles (the kind, shape, size, distribution and surrounding dielectric environment, etc.), the dielectric layers (the crystal quality and thickness, etc.) and the interface states of the heterojunctions. The improved light absorption and enhanced separation efficiency of photo-generated carriers result in the high performance of the devices. The means of a variety of spectral and photoelectric analysis are used to investigate the effects of metal localized surface plasmon resonances and the interface effect of the heterojunctions on the generation, migration, capture, recombination and separation of photo-generated carriers. The inherent relationship between device performance and material microstructures can be revealed. The key factors to determine the performance of the device have been clarified. The implementation of the project is of great scientific significance for understanding the microscopic physical mechanism of self-powered UV PDs. It also provides the references for the application of surface plasmon in other optoelectronic devices.

构建无源的自驱动光探测器是实现微纳光传感器集成化、小型化和多功能化的有效途径。增加紫外区光吸收和促进光生载流子有效分离是实现高性能自驱动紫外光探测器的关键。本项目利用宽禁带II型有序异质结构筑自驱动紫外光探测器，将金属纳米颗粒、介质层引入异质结。通过对金属（种类、形状、尺寸、分布、周围介电环境等）、介质层（结晶质量、厚度等）以及异质结界面态的系统调控，实现金属局域表面等离子体共振效应与异质结界面效应的协同优化，提高光吸收和光生载流子分离效率，获得高性能器件。采用多种光谱手段和光电测试方法研究金属局域表面等离子体共振效应与异质结界面效应对光生载流子产生、迁移、捕获、复合、分离等过程的影响。揭示器件性能与材料结构的内禀关联，澄清影响器件性能的关键因素。本项目的实施，对深入理解自驱动紫外光探测器光响应微观物理机制具有重要科学意义，为表面等离激元在其他光电子器件中的应用提供参考。

集传感和能源供应于一体的具有高灵敏度、超小尺寸和低功耗的自驱动紫外光探测系统可在各种物理环境下实时采集数据，成为传感网络领域发展的一个重要方向。本项目围绕II型有序异质结可控制备，自驱动紫外光探测器设计与性能研究的关键科学和技术问题开展系统的工作。通过金属表面等离子体共振效应（LSPRs）和有序陷光结构设计增加光吸收，利用界面优化、局域场（异质结内建电场、自发极化场等）调控、界面能级匹配等增强光生载流子分离和传输能力，降低光生载流子的复合几率，提高自驱动光探测器的性能。采用多种光谱手段和光电测试方法研究异质结形貌、结晶质量、能带结构等对基本光电特性以及光响应特性的影响机制，澄清影响器件自驱动紫外光探测性能的关键因素，揭示自驱动条件下器件光响应的微观物理机制，实现了几种基于有序异质结的高光响应度，快响应速度的自驱动紫外光探测器。研究结果发现，Al、Au金属颗粒LSPRs耦合作用和热电子效应增强半导体光吸收和载流子界面分离能力。异质结界面引入介质层可有效抑制表/界面态，减少载流子复合，降低异质结器件在零偏压的暗电流，提高光灵敏度和探测率。通过合成过程表面活性剂添加、离子掺杂、半导体化学计量比改变等调节半导体结晶质量和晶面，进而调控材料费米能级，优化异质结界面能带结构，增大异质结内建电场；通过铁电极化场促进了光生载流子的分离和传输，提升异质结光探测器自驱动光探测性能。NiO/TiO2光探测器在自驱动条件下对紫外光的光响应度达到0.86 A/W，探测率达1.6×1013 Jones，响应时间为3 ms。另外，在器件设计、制备和性能研究基础上，拓展了自驱动光探测器在光控逻辑计算、紫外光加密的可见光通讯和视觉传感等领域的应用。本项目的研究结果为开发高性能的自驱动紫外光探测器提供新的方法和思路，相关研究成果发表SCI论文25篇，申请发明专利3项，培养硕士生11名。