Growth Of ?-Ga₂O₃ By MOCVD And Study On Its Solar-Blind Ultraviolet Detector

As a new type of wide bandgap semiconductor material,?-Ga₂O₃ not only has ultra-wide bandgap,high voltage resistance and low loss characteristics,but also has good chemical and thermal stability,which makes it have broad application prospects in the fields of high power device fabrication and solar-blind ultraviolet detection.At present,the research on the material of?-Ga₂O₃ is still in its infancy.The preparation and properties of?-Ga₂O₃ are not systematically and thoroughly studied.Especially,the low quality of?-Ga₂O₃ film limits its application in semiconductor devices.In addition,the research progress of doping of?-Ga₂O₃ is slow.Although some progress has been made in n-type doping,further research is needed to improve its electrical properties.The p-type doping of?-Ga₂O₃ is still a difficult problem.Aiming at the hot and difficult problems in the research of?-Ga₂O₃ materials,based on MOCVD technology,some research work has been carried out on the growth of?-Ga₂O₃ thin films and one-dimensional nanomaterials,the doping of?-Ga₂O₃ thin films and the preparation of?-Ga₂O₃-based solar-blind ultraviolet detectors.The specific research contents are as follows:1.The?-Ga₂O₃ thin films were grown on c-plane sapphire substrates by MOCVD.The effects of growth temperature and pressure on the structure,morphology and optical properties of?-Ga₂O₃ thin films were investigated.By comparing the properties of the films grown under different conditions,the optimum temperature and pressure conditions for the growth of the films were obtained.The room temperature and variable temperature photoluminescence properties of?-Ga₂O₃thin films were systematically studied,and their luminescence mechanism was analyzed in depth.2.The?-Ga₂O₃ thin films were grown on silicon substrates by MOCVD.The effects of growth temperature and buffer layer on the structure,morphology and optical properties of?-Ga₂O₃ thin films were studied.By comparing and analyzing the characteristics of the films grown at different temperatures,the temperature conditions for the growth of the films were optimized.The quality of the films was significantly improved by the growth of?-Ga₂O₃ buffer layer,and the optimum growth temperature of?-Ga₂O₃ buffer layer was obtained.3.One-dimensional nanomaterials of?-Ga₂O₃ were grown on c-plane sapphire substrates by MOCVD with Au as catalyst.The effects of growth temperature and Au particle size on the morphology,crystal structure and optical properties of one-dimensional nano-materials were studied.By adjusting the growth temperature,amorphous?-Ga₂O₃ nanowires were obtained at low temperature,and crystalline nanocolumns were obtained at high temperature.4.Based on MOCVD and using silane as silicon source,the Si doping experiments of?-Ga₂O₃ thin films were carried out.The effect of Si doping on the structure,morphology,optical and electrical properties of?-Ga₂O₃ thin films was studied.It was found that Si doping inhibited the preferred growth of the crystal plane of the?-Ga₂O₃ film?2^—01?to a certain extent.With the increase of Si doping,the surface morphology of?-Ga₂O₃ thin films changed significantly.In addition,the electrical properties of the films can be greatly improved by Si doping.The resistivity of the films can be reduced to 1.79×10^-1??cm,and the carrier concentration and mobility can reach 1.3×10¹99 cm^-3 and 2.68 cm²/V?s,respectively.5.Based on MOCVD,Mg doping experiments of?-Ga₂O₃ thin films were carried out.The effect of Mg doping on the structure,morphology,optical and electrical properties of?-Ga₂O₃ thin films was studied.The results show that with the increase of Mg doping content,the crystalline quality of the films decreases.In addition,the optical band gap of?-Ga₂O₃ thin films increases with the increase of Mg doping,from 4.97 eV to 5.17 eV.6.MSM solar-blind ultraviolet detectors were fabricated based on undoped?-Ga₂O₃ films grown on c-plane sapphire substrates.The device has good light detection performance.Under 15V bias,the dark current is 9.5 nA,the light-dark current ratio is 93.7,and the responsiveness is 0.008 A/W.The response wavelength of the device ranges from 230 to 275 nm,which is in the solar-blind ultraviolet range.7.The undoped and Si-doped?-Ga₂O₃ thin films were grown on p-Si?111?substrates.Based on these structure,the pn junction solar-blind ultraviolet detectors were fabricated.The results show that compared with the devices made of undoped?-Ga₂O₃ thin films,the devices made of Si-doped?-Ga₂O₃ thin films show better rectification characteristics.However,the device based on undoped?-Ga₂O₃ film has better performance in solar-blind ultraviolet detection.Under-15 V bias,the dark current is 6.9 nA,the light-dark current ratio is 7101.1,the responsiveness is 225.9A/W,and the response speed of the device is fast.The relaxation time of the rising edge is 1.64 s,and that of the falling edge is 0.1 s.