Theoretical Calculation And Experimental Study Of Ga₂O₃ Semiconductor Thin Films

In recent years,solar-blind ultraviolet detectors have attracted much more attention due to their wide applications in missile guidance and detection,early warning,ultraviolet communications,ozone monitoring,maritime pollution verification,biological analysis,and public security reconnaissance.Significantly,the research on the development of various novel wide band-gap semiconductor materials has increased as the increasing market demand,which can be used in the new-type solar-blind UV detector with wavelength smaller than 280nm to achieve the military and civilian applications.It is important to notice that gallium oxide(Ga₂O₃)semiconductor is one of the most promising candidates for the solar-blind UV detector,because of its wide bandgap of 4.9 e V,promising physical and chemical stability,higher radiation resistance,lower background noise level,etc.Furthermore,it can realize solar-blind UV detection with higher quantum efficiency and sensitivity.Recently,there are many issues that need to be settled,including the preparation and research on the wide bandgap Ga₂O₃semiconductor and solar-blind UV detector.Therefore,in this thesis,Ga₂O₃semiconductor thin films were prepared using magnetron sputtering technology and study of the UV photoelectric properties after doping modification.This work will be lay the theoretical and experimental foundation for the fabrication of Ga₂O₃semiconductor thin film,the development of UV detectors,and the improvement of photoelectric properties through doping method.The main researches are showed in the following:(1)Based on the plane wave super-soft pseudo-potential method of the density functional theory and the first-principles calculation,the band structure and state density of the intrinsic Ga₂O₃,vanadium(V)and aluminum(Al)doped Ga₂O₃were theoretical calculated and analyzed through establishing the cell structure of Ga₂O₃semiconductor,respectively.It will be lay the theoretical support for the doping modification of Ga₂O₃and their applications in new-type optoelectronic devices.(2)Ga₂O₃thin films were prepared on Si O₂and quartz glass substrates by radio frequency magnetron sputtering coating technology in Ar atmosphere.The sputtering power and deposition time influence on the thicknesses of Ga₂O₃were investigated.X-ray diffraction(XRD),scanning electron microscope(SEM),energy spectrometer(EDS)and other analytical instruments were used to characterize and analyze the microscopic morphology,phase analysis and element composition.Combined with Keithley 4200semiconductor characteristic system,the electrical properties and light response characteristics of the intrinsic Ga₂O₃thin films were analyzed.(3)Ga₂O₃thin films doped with V and Al were fabricated at room temperature by using double-target magnetron co-sputtering technology.The microstructure,surface morphology and chemical composition were analyzed by XRD,SEM,EDS and so on.The effects of different growth conditions on the content of V and Al doped Ga₂O₃thin films were studied.The surface morphology and electrical properties of Ga₂O₃thin films with different doping concentrations of V and Al doping were analyzed,respectively.It is found that Ga₂O₃thin films with Al doping have better electronic performances.