Investigation into epitaxial growth optimization of a novel AlGaN/GaN HEMT structure for application in UV photodetectors

可用于紫外光电探测器的新型AlGaN/GaN HEMT结构外延生长优化研究

In this work,a novel ultraviolet(UV)photodetector(PD)based on AlGaN/u-GaN/p-GaN/u-GaN heterojunction high electron mobility transistor(HEMT)has been developed.This HEMT epilayer is grown using the metal-organic chemical vapor deposition(MOCVD)technique,and the growth parameters,including the AlGaN growth temperature,preheating temperature of the p-GaN layer,and NH3/N2 flow rate,are optimized to improve the quality of the epilayer.The optimized epilayer exhibits a flat surface with a root mean square value of 0.146 nm and low dislocation density.The p-GaN thickness in epitaxial wafers has a significant influence on electrical and UV photoresponse.With a p-GaN of 1µm,the UV PD demonstrates a significant switching ratio and transconductance of 107 and 127.3 mS mm^(-1),respectively.Acting as a UV PD,it also exhibits a high light on/off ratio(I_(light)/I_(dark))of 6.35×10^(5),a high responsivity(R)of 48.11 A W^(-1),and a detectivity(D*)of 6.85×10^(12)Jones under 365-nm UV illumination with light power density of 86.972 mW cm^(-2).The high-performance HEMT and UV detectors,which incorporate p-GaN etchless technology,have been refined through advancements in epitaxial growth and structural design.These improvements solidify the groundwork for large-scale manufacturing of UV communication systems and laser diodes.

本研究制备了一种基于AlGaN/u-GaN/p-GaN/u-GaN结构的高电子迁移率晶体管(HEMT)的紫外光电探测器(UVPD).此结构采用金属有机化学气相沉积技术(MOCVD)生长.本研究对生长参数进行了优化,以提高外延层的质量.最终制备的外延层表面平整,粗糙度仅为0.146 nm,位错密度低.外延结构中的p-GaN层的厚度对器件电学和紫外光响应有显著的影响.研究发现当p-GaN层厚度为1μm时UVPD的开关比和跨导分别达到了10~7和127.3 mS mm^(-1),此外,这款器件的光电流开/关比、响应率和探测率分别高达到6.35×10^(5),48.11 A W^(-1)和6.85×10^(12)Jones.这种无p-GaN刻蚀技术为紫外线通信系统和激光二极管的大规模制备奠定了坚实的基础.