Preparation And Photoelectrical Properties Study Of Gallium Oxide Thin Films By Magnetron Sputtering Method

Gallium oxide as a wide direct band-gap semiconductor?band gap about 5 eV?,has excellent application prospects in the field of high performance devices owing to its excellent physical and chemical stability and excellent photoelectric properties.In this paper,the?-Ga₂O₃ thin films were obtained by post-annealing at high temperature called solid-phase crystallization after RF magnetron sputtering deposition.In order to improve the films quality,the influence of preparation technology and post annealing treatment on the properties of Ga₂O₃ film have been studied in detail.The interdigitated electrodes array has made on Ga₂O₃ thin films to fabricate MSM UV photodetector and the performance of the detector was analysed.The main research work of this paper is as follows:?1?To explore the effect of a series of process parameters including sputtering power,work pressure,oxygen and argon ratio on microscopic crystalline structure and photoelectric properties of thin films,the Ga₂O₃ thin films were grown using gallium oxide target by RF magnetron sputtering method on sappire?0001?substrate.Analysis of crystal structure,crystal orientation,morphology,grain size,optical transmission of thin films were obtained by several characterization methods including XRD?SEM?UV-Vis?PL.Optimized parameters of Ga₂O₃ films with good quality is:sputtering power 200 W,working pressure 1.2 Pa,oxygen to argon ratio 4:38,growth sputtering time 120 min,post annealing temperature 800?,and annealing time 120 min.?2?The Ga₂O₃ thin films wer prepared on silicon?111?substrate by RF magnetron sputtering.Since the Si substrate is easily oxidized to amorphous SiO₂ after cleaning and the crystal quality of the Ga₂O₃ thin film will be reduced,the deposition of a low oxygen buffer layer is required before deposition,which can avoid the formation of a-SiO₂ and reduce the influence of Si and thin film mismatch.Exploration and analysis of the influence of parameters of low oxygen layer on properties of the films.The optimum deposition parameters are working pressure 1 Pa,sputtering power 100 W,argon flow rate 42 sccm,and sputtering time 60 min.By changing a series of basic process parameters,the results show that the increase of sputtering power will make the crystalline quality of the film becomes better,and the grain size becomes larger.There are two mechanisms accounting for working pressure affecting the growth of thin films:gas particles collision probability and oxygen concentration.Increasing pressure make the crystal quality deteriorates firstly and becomes better.The influence of sputtering time on the film is mainly shown in the thickness changing,and the thickness increases with time.With the annealing temperature increasing,the crystalline quality of the film gradually becomes better.?3?MSM structural solar-blind detector was fabricated by preparation of the interdigitated electrode on the Ga₂O₃ thin film using standard photolithography and lift-off techniques.At 30 V bias,the photodetector based on a-GaO_x thin film exhibits a spectral response of 122.69?A W^-1at a wavelength of 256 nm.In order to increase the conductivity of the film,a Ga₂O₃ thin film doped with Sn under different sputtering power was prepared and an MSM type photodetector was fabricated based on Ga₂O₃:Sn thin film.It was found that the response of the device was improved.The photodetector based on Ga₂O₃:Sn film was prepared at 200 W has the maximal response and photocurrent.It were 41.3 mA W^-1and 23.73 mA,respectively.