Study On Growth And Detector Of GaN-based Materials With Micro-nano Structures

GaN-based materials are one of the typical representatives of the third generation semiconductor materials.They are direct wide-gap materials with excellent photoelectric characteristics and good stability.GaN-based materials improve the performance of high-frequency,high-temperature and high-voltage high-power devices and photoelectric devices.However,at present,the performance of GaN-based ultraviolet?UV?photoelectronic devices is still not ideal,and the main reasons include poor crystal quality of materials and low level of p-type doping.The technical route for improving the performance of GaN-based detectors is mainly divided into two aspects: material growth and device design.This dissertation focuses on device design and aims to study on high-performance,multi-functional photodetectors based on GaN-based detectors with new structures.In this dissertation,we focus on new methods to improve the performance of GaN-based UV photodetectors by using micro-nano structures.This dissertation is mainly divided into three parts: the first part is based on the preparation of Al surface plasmon and enhancement on Al GaN-based UV photodetector,and the in-situ preparation of Al nanoparticles by metalorganic chemical vapor deposition?MOCVD?is developed.The second part is the study on GaN quantum dots growth and high performance graphene hybride structure detector.The third part is the study on GaN UV /MoS₂ visible light dual-color detector.The main achievements of this dissertation are as follows.1.Based on the MOCVD growth kinetics principle and First principle calculation,the in-situ MOCVD growth of Al nanoparticles was proposed and realized.As an effectivel plasmon material for UV photoelectric devices,the current preparation methods of metal Al nanoparticles are all ex-situ preparation.Based on the growth principles and theoretical calculations,our study proposed and achieved in-situ preparation of Al plasmon nanoparticles by using MOCVD method.After the growth of Al GaN epi-layer by MOCVD,Al organic metal source?TMAl?is introduced separately to achieve in situ fabrication of Al nanoparticles The significant photoresponsivity improvement of Al GaN-based UV photodetectors was achieved,and an maximum enhancement in the responsivity of Al GaN-based detectors is over 9 times.The growth mechanism and the gain mechanism of in-situ fabrication Al nanoparticle were also analyzed and studied.2.The growth of self-organizing GaN quantum dots was realized,and the graphene grown by CVD was transferred to the surface of GaN quantum dots to form a hybride structure detector and high efficient photoresponsivity was achieved.Using droplet epitaxial method,the growth of GaN quantum dot structure was realized by MOCVD,the surface morphology,composition and photoluminescence characteristics were studied,and the formation mechanism and growth evolution of the quantum dot were also analyzed.Hybride photodetector with GaN quantum dot / graphene structure was obtained.By transferring the graphene materials grown by chemical vapor deposition?CVD?onto GaN quantum dot sample,a new photodetector with zero dimension/two dimension was obtained to realize high effective optical detection with the peak responsivity reached 9.36 A/W at 10 V bias.3.Monolithic integration of GaN-based UV detector and MoS₂-based visible detector is realized by growing high quality MoS₂ on GaN wafer.High quality monolayer MoS₂ was grown on lattice-matched GaN substrate by CVD method and through normal semiconductor process to achieve high performance monolithic integrated UV-visible dual-color detector.The peak response of GaN-based UV detector is 172.12 A/W,and that of MoS₂–based visible detector is 17.5 A/W.At the same time,the dual-color detectors also achieved high photoconductive gain,high external quantum efficiency,high normalized detectivity and low noise equivalent power.