InAs量子点/ZnO纳米柱异质结的制备及光探测性能研究

Semiconductor nanomaterials have become the research hot topic in optoelectronic application. This project addresses a multi-band photodetection based on the heterojunction of InAs quantum dots(QDs)/ZnO nanorod arrays. The band alignment of this heterojunction is designed as "type-II" structure in order to separate electrons and holes effectively. In this detector, the UV response arises from the interband absorption of UV radiation by ZnO, and the visible response is due to the absorption in the InAs QDs, in addition, photocurrents will be increased dramatically by the process of multiple exciton generation (MEG) of InAs QDs excited by high energy photons. Meanwhile the detection range will be expanded to ultraviolet or deep-ultraviolet band. In the course of project, we plan to investigate the size, density and growth mechanism of ZnO nanorod arrays and the method to control the size of InAs QDs, the dependence of band structure on the size of InAs QDs, which we believe the control of size of QDs has the important effect on the detector performance. The photoconductive response of InAs QDs/ZnO nanorods heterojunciton is also investigated. The dependence of detection perforamance on heterojunction structure, InAs QDs and ZnO nanorods properties and carriers transport mechanism will be studied systematically. In order to increase the detection efficiency, the threshold of multiple exciton generation (MEG) will be determined. A more complete study of this project will provide fundamental understanding and techniques of the increase of responsitivity of ZnO/InAs QDs heterojunction in multi-band photodetection application.

半导体纳米材料在光电领域的应用一直是国际上的研究热点。本课题正是基于这样一个着眼点，以光探测器为应用背景，提出采用InAs量子点/ZnO纳米柱阵列异质结获得室温多波段的光响应。本课题基于二者形成II型能带，有效分离光生电子和空穴，除可获得来自于ZnO纳米柱和InAs量子点带间吸收的紫外和可见波段光响应外，还可通过高能入射光子导致的多激子产生效应(MEG)提高光探测率并将探测扩展至紫外或深紫外波段。本课题研究ZnO纳米柱阵列的尺寸、密度和生长机制；掌握InAs量子点尺寸控制技术，研究InAs量子点尺寸和能带的依赖关系，满足II型能带的要求；研究InAs量子点/ZnO纳米柱阵列异质结的多光谱响应；研究器件结构、材料性质与器件性能的关系，研究载流子注入机制及复合机制与器件结构的关系；研究InAs量子点MEG效应阈值条件，提高器件探测效率；探索提高光响应度、降低暗电流的物理方法和技术手段。

本项目的研究目标主要是针对紫外-红外双色和多光谱探测的需求，开展的以宽带隙半导体ZnO为主体，以窄带隙半导体的量子点修饰，由于二者能带的巨大差距，形成II型异质结。主要研究内容包括ZnO纳米材料的制备工艺及生长机制和光电性质；量子点的制备及生长机制及光电特性；异质结探测器的制备及性能研究。通过改变锌源种类获得了形貌可控的ZnO纳米材料；制备了量子点材料，实现了量子点的尺寸和分布的可控性；制备了异质结探测器，通过调控量子点与纳米线的界面，可获得宽光谱的探测性能。通过二者界面的调控，拓展了光谱范围，为实现多光谱和宽光谱探测提供了新途径。