量子点嵌入共振隧穿二极管用于高灵敏度紫外光探测研究

Highly sensitive ultraviolet light (UV) detector has important applications in the fields of national defense and civilian use. Traditional solid-state UV single photon detectors are mainly avalanche photodiodes (APD). Although the avalanche gain is very high, the high avalanche voltage of APD not only requires a dedicated avalanche quenching circuit, but also brings problems such as tunnel current leakage and red shift of the photo response spectrum. In view of the technical bottleneck of the avalanche multiplication mechanism, this project proposes a quantum dot embedded resonant tunneling diode for high sensitivity UV detection, which has advantage of both high UV-generated carrier multiplication gain and detection voltage that is one order of magnitude lower than that of avalanche diodes. The project focuses on the effects of polarization and defects of nitride materials on resonant tunneling stability, exploring the design of non-polarized quantum wells on c-GaN substrates, eliminating the polarization field of resonant tunneling structures, and improving the stability of resonant tunneling. Based on this, the project investigates the UV detection mechanism of trapping photo generated holes by quantum dots to increase resonance tunneling current, and studies the electron-hole spatial separation mechanism for polarized InGaN quantum dots. Combining device-level physical simulation and prototype device preparation, the project would establish a UV-generated carrier amplification model, which provides scientific basis for the application of quantum dot resonant tunneling diode for highly sensitive UV detection.

高灵敏紫外光探测技术在国防和民用领域都有重要应用。传统的固态紫外单光子探测器以雪崩二极管为主，虽然雪崩增益很高，但单光子探测需要雪崩淬灭电路，雪崩高压也带来了隧穿漏电、响应光谱红移等问题。针对雪崩探测机理技术瓶颈，本项目利用量子点嵌入共振隧穿二极管进行高灵敏紫外探测，既具备高紫外光生载流子增益，且探测电压比雪崩二极管低一个量级以上。项目重点研究氮化物材料极化、材料缺陷对共振隧穿稳定性影响，探索c-GaN衬底无极化量子阱设计，消除共振隧穿结构极化场，提高共振隧穿稳定性；在此基础上重点研究量子点俘获光生空穴增加共振隧穿电流的紫外探测机理，研究InGaN极化量子点的电子-空穴空间分离机制，结合器件级物理仿真和原型器件制备，建立紫外光生载流子的倍增放大模型，为量子点共振隧穿二极管应用于高灵敏紫外探测提供科学依据。

电晕检测、尾焰探测等应用需要高灵敏的紫外光探测器件。受限于Franz-Keldysh效应的高压光谱展宽，目前固态雪崩探测器的光谱截止特性不如真空光电器件。本项目利用量子点调控共振隧穿机理进行高灵敏紫外探测，实现了低探测电压下的光电倍增，从原理上避开了雪崩探测器件高探测电压下的光谱展宽难题。本项目主要研究内容包括量子点耦合共振隧穿二极管结构的器件级仿真，量子点耦合共振隧穿二极管的外延生长及原型器件制备研究，获得量子点耦合共振隧穿二极管的电学特性，完成初步紫外响应测试。本项目的重要结果包括建立了量子点嵌入共振隧穿结构的紫外光生载流子倍增放大模型，完成了量子点嵌入共振隧穿二极管原型器件的制备，原型器件在低温下实现器件探测电压<5V，紫外光生载流子增益大于1000。本项目发表SCI及会议文章4篇，申请发明专利两项。本项目验证了量子点调控隧穿机理用于高性能紫外探测的可行性, 为固态器件最终替代紫外真空器件提供了一种新的探测机理。