Preparation And Ultraviolet Detection Performance Of Cu Doped β-Ga₂O₃ Films By CVD

Gallium oxide（β-Ga₂O₃）,as the third generation of wide band gap semiconductor material,has the characteristics of large band gap width（4.9 e V）,strong breakdown electric field,absorption edge is located in the solar blind ultraviolet band（200-280 nm）,and has high transmittance in the near ultraviolet and the whole visible band.Therefore,β-Ga₂O₃is a very suitable material for making solar blind UV photoelectric detectors.At present,there are few studies on p-typeβ-Ga₂O₃materials,but the preparation of p-typeβ-Ga₂O₃materials is very important for the application ofβ-Ga₂O₃related devices,so the successful preparation of p-typeβ-Ga₂O₃materials is particularly critical.To solve the above problems,this thesis uses chemical vapor deposition technology to grow Cu dopedβ-Ga₂O₃films on sapphire substrate and n-Si substrate,and based on this production of Cu-dopedβ-Ga₂O₃films MSM photoconductive UV detector and Cu-dopedβ-Ga₂O₃film/n-Si heterojunction self-powered UV detector.The UV detection performances of these two devices is also studied.The main contents of this thesis are as follows:（1）Theβ-Ga₂O₃thin films with different Cu doping contents were grown on sapphire substrates by chemical vapor deposition method,and the morphology,crystal structure and optical properties ofβ-Ga₂O₃films were measured.The test results show that the surface ofβ-Ga₂O₃films with different Cu contents is relatively smooth,and the（-201）diffraction peak positions shift to the lower degree side with increasing Cu content,which indicates that Cu²⁺is substituted for Ga³⁺into theβ-Ga₂O₃lattice.In addition,a photoconductive UV detector with MSM structure was prepared by evaporation of Au on a Cu-dopedβ-Ga₂O₃film,and its UV detection performance was studied.The results show that the photocurrent value of the devices increases with the increasing Cu contents.The I_light/I_darkratio is about 3.8×10²of 2.4%Cu content device under 254 nm light with a light intensity of 221μW/cm²at 10 V.The rise time and decay time of 0.11 s and 0.13 s,respectively.Furthermore,the responsivity and external quantum efficiency can reach up to 1.72 A/W and 841%under 254 nm light with a light intensity of 64μW/cm².（2）The Cu dopedβ-Ga₂O₃film was grown on low resistivity n-Si substrate by CVD method.The morphology of sample showed that the surface of Cu-dopedβ-Ga₂O₃film was flat and compact.On this basis,Al and Au electrodes deposited on the back of n-Si substrate and on the surface of Cu-dopedβ-Ga₂O₃films,and then Cu-dopedβ-Ga₂O₃films/n-Si heterojunction self-powered solar blind photodetectors were prepared.It is found that the current-voltage image of the heterojunction detector exhibits typical rectifying behavior.The I_light/I_darkratio of the device is 1.0×10³under 254 nm light under 0 V,and a fast rise time(τ_r1,τ_r2)and decay time(τ_d1,τ_d2)of（0.07 s,1.18 s）and（0.09 s,1.12 s）,respectively.The responsivity and external quantum efficiency can reach up to 0.91 A/W and 445%under 254nm light with a light intensity of 144μW/cm².This study provides a new idea and a good research basis for the preparation of p-typeβ-Ga₂O₃material and its solar blind UV detector.