Theoretical Calculations And Experimental Research Of ?-Ga₂O₃ Semiconductor Thin Film

UV detectors have a broad application prospect in the fields of missile launch detection,space and astronomical research,environmental monitoring,UV radiation calibration and monitoring,optical communication,etc.Currently,a variety of wide bandgap semiconductor materials have been studied and applied in the fabrication of UV photodetectors,such as gallium nitride(Ga N),silicon carbide(Si C),zinc oxide(Zn O)and gallium oxide(Ga₂O₃),and so on.Compared with the narrow bandgap Si semiconductor materials,these wide bandgap semiconductors electronic and optoelectronic devices have lots of advantages,including higher breakdown resistance,stronger radiation tolerance,and higher device operating power.New-type wide bandgap semiconductor devices have showed more outstanding application potential in the development of"solar-blind region"detectors.Therefore,novel widegap semiconductor materials have attracted a great deal of research interest in recent years,which developed rapidly in the development of semiconductor materials and devices.Presently,the third generation compound semiconductors represented by Si C and Ga N have been widely used in the microwave,RF and power amplifier applications,which have received more and more attention.Moreover,the devices based on the third generation semiconductor have played an important role in the application of high power,high temperature and high pressure,which cannot be achieved by traditional Si semiconductor devices.Simultaneously,economic benefit form market is enormous.Due to larger band gap(4.5-5.2e V),higher breakdown electric field intensity(6-8m V/cm),larger Baliga's figure of Merit,epitaxial growth on heterogeneous substrates,and low cost,Ga₂O₃has showed stronger market competitiveness compared with Si C and Ga N wide band gap semiconductor materials.Thus,Ga₂O₃is expected to be widely used in the three important fields in the future information age,which are construction of intelligent vehicles,5G or 6G communication and the internet of things.In traditional semiconductor UV detector fabrication,the detector is fabricated on the broad gap semiconductor epitaxial layer or thin film by planar machining methods.Therefore,researching on the best preparation conditions of Ga₂O₃semiconductor thin film materials and the influence of various doping elements on material properties are the key problems in the application of Ga₂O₃semiconductor materials and devices.Hence,aiming at the current situation that our China is still lagging in the preparation and device research of large-size and high-quality?-Ga₂O₃crystal materials,as well as the energy bands of?-Ga₂O₃semiconductor thin films under various doping conditions,in the thesis,theoretical calculation of?-Ga₂O₃semiconductor thin films under different doping conditions,the preparation of?-Ga₂O₃semiconductor thin films using RF magnetron sputtering technology,and the optimal preparation parameters were researched,respectively.In detail,the energy band structure,density of states and partial density of the intrinsic?-Ga₂O₃,Sn-doped?-Ga₂O₃and Cu-doped Cu/?-Ga₂O₃supercells are theoretically calculated.Subsequently,the intrinsic?-Ga₂O₃,Sn-doped Sn/?-Ga₂O₃,and Cu-doped Cu/?-Ga₂O₃thin films were prepared by RF magnetron sputtering technology under different sputtering power and annealing temperature conditions.In the end,the?-Ga₂O₃thin film diode with different channel widths were fabricated by using of mask deposition technology,and the photoelectric characteristics of the synthesized?-Ga₂O₃thin film diode devices were researched.The results can offer some theoretical and experimental reference to the modification of?-Ga₂O₃semiconductor thin films materials by doping,the preparation and application of related devices in the future.The main research contents in the thesis are as follows:1.In the theoretical calculation,1×1×1?-Ga₂O₃semiconductor supercell was established by using the first-principles plane wave ultra-soft pseudopotential method with the CASTEP module of MS 2018 software.The energy band structure,density of states and partial density of the intrinsic?-Ga₂O₃,Sn-doped Sn/?-Ga₂O₃,and Cu-doped Cu/?-Ga₂O₃supercells were calculated and compared,respectively.2.The intrinsic?-Ga₂O₃thin film diodes with different channel widths were fabricated on Si O₂/Si substrate at different sputtering powers by masking RF magnetron sputtering method,and then annealed at different temperatures.Thereinto,Si O₂can be formed on the Si substrate by thermal oxidation.The microstructure,surface morphologyand chemical element composition of the fabricated intrinsic?-Ga₂O₃thin films were analyzed by analytical instruments,including XRD,SEM,and EDS.The electrical conductivity of the prepared intrinsic?-Ga₂O₃thin films under different conditions was measured with four-probe testing method.The IV and optoelectronic properties of the intrinsic?-Ga₂O₃thin-film diode detectors were analyzed using a Keithley-4200SC semiconductor characterization system.3.Sn-doped Sn/?-Ga₂O₃and Cu-doped Cu/?-Ga₂O₃semiconductor thin films were prepared at different sputtering power by a dual-target RF sputtering method,and then annealing at different temperatures.Subsequently,Sn-doped Sn/?-Ga₂O₃and Cu-doped Cu/?-Ga₂O₃semiconductor thin film diode detectors with different channel widths were fabricated by the masking deposition technique.The microstructure,surface morphology,and chemical element composition of the semiconductor thin films under different doping conditions were investigated using XRD,SEM,EDS and other analytical instruments.The electrical conductivity of Sn-doped Sn/?-Ga₂O₃and Cu-doped Cu/?-Ga₂O₃semiconductor thin films were measured.In the end,the IV and optoelectronic properties of the fabricated diode detectors based on Sn-doped Sn/?-Ga₂O₃and Cu-doped Cu/?-Ga₂O₃semiconductor thin films under different conditions were analyzed with a Keithley-4200SC semiconductor characterization system.From the results,it can be found that the IV and optoelectronic characteristics of synthesized?-Ga₂O₃semiconductor thin film diode devices were significantly improved after Sn and Cu elements doping.The research and conclusions will be more favorable for the development of high power?-Ga₂O₃semiconductor devices and detectors,which provides reference for the future research.