基于Ga2O3/SiC异质结的新型高增益紫外光电晶体管研究

Ultraviolet detection technology has a broad application prospect in fields such as HV arc detection, extreme weather warning and missile defence. In view of high operating voltage required of the avalanche photodiodes (APDs) based on wide bandgap semiconductor, this project proposed a novel device structure, named punchthrough enhanced gallium oxide/ silicon carbide heterojunction ultraviolet phototransistor, which could achieve both low operating voltage and high internal optical gain. The first research content mainly focus on establishing the simulation model of gallium oxide/ silicon carbide heterojunction optical device by studying the characteristic parameters such as the band alignment and the interface defect. Next, the optimal device structure parameters will be obtained by analyzing the mechanism between the epi-layer parameters and the internal gain of the phototransistors. Furthermore, some key processes, such as dry etching of gallium oxide and special passivation for both gallium oxide and silicon carbide, will be particularly investigated. Finally, we are going to fabricate the high performance gallium oxide/ silicon carbide heterojunction ultraviolet phototransistor with operating voltage less than 5 V and internal gain greater than 2000 simultaneously.

紫外探测技术在高压电弧检测、极端天气预警以及紫外制导等领域具有广泛的应用前景。针对宽禁带半导体雪崩光电二极管(APD)工作电压较高的研究现状，本项目尝试提出一种新型基区穿通型Ga2O3/SiC异质结紫外光电晶体管结构，期望实现低工作电压和高内部增益兼顾的器件特性，为此领域的发展可以提供新的研究思路和方法。具体研究内容为拟通过研究Ga2O3/SiC异质界面的能带带阶和界面缺陷等关键参数，建立Ga2O3/SiC异质光电器件仿真模型；分析基区穿通时外延层参数与光电子内部增益作用机制，得到优化的器件结构参数，最终研制出高性能的Ga2O3/SiC异质结紫外光电晶体管，在工作电压小于5V时，探测器的内部增益大于2000。

紫外探测技术是近年来快速发展的光电探测技术之一，其不仅在导弹预警和紫外通信等军事范围具有重要意义，同时在火灾雷电预警、高压线破损检测以及细胞癌变检测等民生领域也有广泛的应用前景。本项目围绕碳化硅/氧化镓异质结构紫外探测器开展了多方面研究工作，主要内容及成果如下：建立了氧化镓禁带宽度模型、不完全离化模型、迁移率模型和复合模型等主要材料模型，形成了氧化镓/碳化硅异质结构器件物理模型，可以有效支撑此类电子器件的设计和分析；开展了氧化镓材料表面钝化工艺研究，得到了不同钝化层方案下的漏电机制、界面缺陷机理以及界面态、固定电荷等重要参数；制备了氧化镓/碳化硅异质结，分析了薄膜质量以及异质结能带分布情况，并实现了具备自供电、低暗电流以及高响应速度等优点的氧化镓/碳化硅异质结构紫外探测器；设计并实现了背入射式碳化硅基光电晶体管，光响应度在254nm波长下达到0.1A/W，光暗电流比达到五个数量级，不同光功率下线性度较好，同时器件的响应时间较快，上升时间为200ms，下降时间为80ms，该器件是国际上为数不多的宽禁带半导体光电三端器件。项目累计发表与研究内容相关的SCI论文9篇，申请并授权PCT美国专利1项，申请并授权中国发明专利7项，培养已毕业博士生2名，培养已毕业硕士生2名。