局域表面等离激元诱导的金属/ZnO双肖特基结多波段探测性能研究

Semiconductor photodetector has been research hot topic in recent years. In order to meet the demands of high responsivity and multi-band photodetection, plasmonic metal nanostructures/ZnO tandem Schottky junctions have been proposed to achieve multi-band optical response and enhance the performance of semiconductor photodetectors. Generally, localized surface plasmon resonance (LSPR) induced by noble metal nanostructures can enhance the absorption cross section of semiconductors, and improve the absorption efficiency, which could effectively enhance the responsivity of the ZnO ultraviolet photodetector. Another important property of these metal nanostructures is their propensity for generating energetic or“hot”electron-hole pairs by plasmon decay. These photoexcited hot electrons can inject into the semiconductor over the Schottky barrier, contributing to a detectable photocurrent. Due to the Schottky barrier is much less than the band gap of ZnO, the infrared response can be obtained by the charge separation of surface plasmon-driven hot electron. Meanwhile, dark current of detectors can be effectively decreased due to the generation of space charge region at the interface of metal and ZnO nanoschottky diodes. This project addresses a multi-band photodetection based on the tandem Schottky junctions of noble metal/ZnO. In the course of project, we plan to investigate the method to control the size and morphology of metal particles, the dependence of localized surface plasmon resonance wavelength on the size and morphology of metal nanostructures, the growth parameter of metal particles for LSPR from the ultraviolet to infrared region. The dependence of carriers transport mechanism on metal particles and ZnO properties will be studied systematically. A more complete study of this project will provide fundamental understanding and techniques of the high responsivity, low dark current and multi-band photodetection of ZnO based photodetector.

半导体光探测器一直是国际上的研究热点。本课题正是以高响应度、多光谱调谐的光探测器为应用背景，提出以贵金属颗粒/ZnO构建的双肖特基结获得室温紫外至红外多波段响应的探测器。基于贵金属颗粒产生的局域表面等离激元可显著提高半导体光吸收效率的特性，提高ZnO紫外探测器的光响应度。同时，局域表面等离激元衰减时激发出的高能量热电子具有足够能量可跃过金属/ZnO肖特基结至ZnO的导带，形成光电流。由于肖特基势垒远小于ZnO的带隙，调控金属颗粒尺寸和形貌可实现红外波段光探测。金属/ZnO肖特基结也可有效降低暗电流。本课题重点研究多波段响应的串联双肖特基结构的构建；研究局域表面等离激元共振波长与金属颗粒尺寸和形貌的依赖关系，满足紫外探测增强及热电子跃迁的要求；研究ZnO和金属颗粒的形貌对肖特基势垒、界面及载流子输运的影响；探索提高光响应度、降低暗电流的方法和技术手段，提供实现ZnO基多波段探测器的新途径。

本项目研究了贵金属颗粒产生的局域表面等离激元可显著提高半导体光吸收效率的特性，提高宽禁带氧化物半导体ZnO和TiO2紫外探测器的光响应度。同时，局域表面等离激元衰减时激发出的高能量热电子具有足够能量可跃过金属/宽禁带氧化物半导体肖特基结至宽禁带氧化物半导体的导带，形成光电流。由于肖特基势垒远小于宽禁带氧化物半导体的带隙，调控金属颗粒尺寸和形貌可实现红外波段光探测。金属/宽禁带氧化物半导体肖特基结有效降低暗电流。本课题重点研究多波段响应的串联双肖特基结构的构建；研究局域表面等离激元共振波长与金属颗粒尺寸和形貌的依赖关系，满足紫外探测增强及热电子跃迁的要求；研究了宽禁带氧化物半导体和金属颗粒的形貌对肖特基势垒、界面及载流子输运的影响。