Preparation And Application Of Preferential Orientation Of The Gallium Oxide Film

Gallium oxide Ga₂O₃ as a wide bandgap semiconductor oxide material,its unique properties determine its broad prospects in the field of optoelectronics,piezoelectric,gas sensitive,photosensitive,and other potential applications.At present,the research of Ga₂O₃ at domestic and abroad is mainly focused on the preparation of good performance UV blind detectors using polycrystalline and single crystal Ga₂O₃.Single crystal Ga₂O₃ as the device active layer can get good UV detection performance,but the preparation cost is high.The crystalline quality of the polycrystalline Ga₂O₃ film is poor,and its conductivity is so poor as the active layer of the device not good for the detector.Ga₂O₃ thin films with high preferential orientation are interposed between polycrystals and single crystals.As we know,the grain morphology and grain boundary structure of the film will have a significant impact on its performance.Ga₂O₃ thin films with high preferential orientation have great optical and electrical properties.On the basis of the above,Ga₂O₃ thin film was fabricated by magnetron sputtering method using silicon carbide and sapphire as substrates.Considering the lattice mismatch between Ga₂O₃ and substrate,select the crystal planes parallel to b axis for the growth surface could achieve the smaller lattice mismatch with the substrate.And also conducive to improving the crystalline quality of the film,and can effectively improve the film conductivity.Therefore,this paper based on the preparation of preferrentially oriented gallium oxide films on silicon carbide and sapphire substrates and study their applications as GaN buffer layers and UV detectors.The effects of RF power,sputtering pressure,film thickness and annealing temperature on the surface morphology and structure of Ga₂O₃ films were studied by magnetron sputtering on silicon carbide substrates.The experimental results show that the RF power,sputtering pressure and film thickness have some influence on the crystal quality of Ga₂O₃ thin films,but little influence on the structure of Ga₂O₃ films.The results show that the annealing temperature is increased and the crystal quality of the Ga₂O₃ film is obviously improved,which indicates that the annealing can effectively release the internal stress of the film.If the annealing temperature is too high,the crystal structure of the film will be destroyed and the preferential orientation of the film will be deteriorated.In addition,annealing can also affect the bandgap and resistivity of the films,which is mainly due to the change of oxygen vacancy and dislocation density on the surface of the film.The Ga₂O₃-based MSM UV detector was fabricated and the effect of annealing temperature on the detector performance was studied.The experimental results show that the prepared Ga₂O₃-based UV detector has a good light response to 254 nm UV light.The response time of the detector is shortened with the increase of the annealing temperature,and the light-dark current ratio first increases and then decreases with the annealing temperature increasing.The effects of annealing temperature on the crystal quality,chemical composition and photoelectric properties of Ga₂O₃ thin films were studied.Then the GaN films were prepared by laser pulse deposition and analyzed the effect of buffer layer on the crystalline quality of GaN thin films.The experimental results show that gallium nitride and sapphire are poor in wettability and can not form gallium nitride thin films with better crystal quality.Inserting gallium oxide film as the buffer layer will obviously improve the crystalline quality of the gallium nitride epitaxial layer,and the gallium nitride crystal quality obtained by annealing at 900 ? is the best.