Preparation And Photoelectrical Properties Study Of Ga₂O₃:Sn Thin Films

Wide-gap semiconductors have broad and important prospects in solar-blind ultraviolet detection.Therefore,in recent years,the third-generation semiconductors represented by Ga₂O₃:Sn have become a hot topic of research and discussion.Among them,Ga₂O₃:Sn film has good chemical stability and photoelectricity.Excellent performance,is one of the ideal materials for the preparation of a new generation of deep ultraviolet detectors.The magnetron sputtering method has low cost,wide application,low working temperature,and is suitable for large-scale application in industrial production.Therefore,this thesis uses RF magnetron sputtering to realize Ga₂O₃:Sn films and solar-blind ultraviolet detectors on sapphire substrates and silicon substrates,and studies their photoelectric detection performance:(1)The Ga₂O₃:Sn film is prepared on a sapphire substrate,and the in-situ annealing temperature is not enough to crystallize Ga₂O₃:Sn.Increasing the annealing temperature will widen the optical band gap of the film.However,an excessively high annealing temperature will affect the optoelectronic properties of the device.When the oxygen content in the sputtering atmosphere is too low,the doping ratio of Sn will be increased,reducing the optical band gap of the film and also reducing the crystal quality;The preparation of Ga₂O₃:Sn films under low pressure conditions will regulate the band gap,but also damage the crystal quality;In the intermediate pressure region,the crystal quality is better and the crystal grain size is uniform.(2)Prepare Ga₂O₃:Sn film on silicon substrate and grow low-oxygen buffer layer to obtain higher quality crystals;Too high sputtering power will increase the surface roughness of the film and deteriorate the degree of crystallinity;The growth of Ga₂O₃:Sn film on the substrate is similar.The doping ratio of Sn can be adjusted by changing the oxygen-argon ratio;increasing the annealing temperature will gradually increase the grain size of the Ga₂O₃:Sn film,but high annealing temperature will damage the film compactness.(3)For Ga₂O₃:Sn devices on a silicon substrate,doping with Sn can improve the sensitivity of the device,but it will also prolong the relaxation time of carriers;The device has a very high temperature at low annealing temperatures.The responsivity and external quantum efficiency can reach 3.467 A/W,1694%,but increasing the annealing temperature can speed up the carrier recombination speed.For the Ga₂O₃:Sn device on the sapphire substrate,the dark current of the sample is one to three orders of magnitude lower than that of the Si substrate.This is because the polycrystalline film grown on the sapphire has good crystal quality and fewer oxygen vacancies.