Research On Photodetectors Based On β-Ga₂O₃/γ-CuI Heterojunction

In recent years,third-generation semiconductor materials with a band gap greater than 2.3 eV,such as GaN,SiC,and Ga2O3,have been widely studied.Such materials have the advantages of wide band gap,high electric field breakdown strength and saturation electron drift velocity,as well as good chemical and thermal stability,which are very suitable for the study of high-performance semiconductor devices.The forbidden band width ofβ-Ga2O3 ranges from 4.2 eV to 4.9 eV,covering the main UVC region,which is an ideal material for the preparation of solar-blind UV photodetectors.The heterojunction structure based on β-Ga2O3 is an effective attempt to widen the detection area,so it has become a research hotspot in recent years.In this paper,a heterojunction photodetector based on gallium oxide thin films was designed and fabricated,the growth methods of two gallium oxide thin films were explored,and the positive effect of the heterojunction structure on the performance of the photodetector was verified.The main research results are as follows:(1)The optimal growth parameters of single crystal β-Ga2O3 thin films were explored by magnetron sputtering and metal organic compound chemical vapor deposition,respectively.After preliminary electrical tests and detailed morphological characterization,it was verified that a smooth and dense single-crystal β-Ga2O3 film was successfully grown on the substrate by metal-organic compound chemical vapor deposition method,and had better properties.(2)Vertically structured β-Ga2O3/γ-CuI heterojunctions were fabricated on sapphire substrates by metal-organic chemical vapor deposition(MOVCD)and spin-coating methods.X-ray diffraction(XRD),scanning electron microscopy(SEM))technique to characterize the heterostructure,and the formed devices were characterized electrically by the optoelectronic test system.The fabricated β-Ga2O3/γ-CuI photodetector was tested,and it was found that under 254 nm illumination,when the bias voltage was-5 V,the dark current of the device was 0.47 pA,the photocurrent was-50.93 nA,and the photocurrent was-50.93 nA.The dark current ratio reaches 1.08×105.The device has stable and fast response speed in different wavelength bands.Under 254 nm illumination,the rise time(τr)and decay time(τd)are 1.98 s and 0.52 s,respectively;while under 365 nm illumination,the rise time(τr)and decay time(τd)were 4.93 s and 12.04 s,respectively.Clearly resolvable I-t response(photocurrent on the order of 10-10 A)at tiny light intensity(1 μW cm-2).