Preparation And Photoelectric Properties Of Graphene Heterojunction Of InAsSb And β-Ga₂O₃

Graphene has a high mobility with a single-layer hexagonal structure,has good optical,thermal,mechanical and other properties,and has a high electron mobility at room temperature.Good electrical conductivity and the characteristics of being a two-dimensional material make it have excellent application potential in detectors,sensors,catalysis,energy storage,etc.Photodetectors have extremely important applications in military communications,semiconductor manufacturing,lasers,civil flame detection,and environmental monitoring.At present,the main research hotspots of photoelectric detectors are:1.Uncooled infrared detectors 2.The third-generation wide-bandgap semiconductor devices.Infrared detection material In As Sb is suitable for application in the mid-wave infrared band due to its extremely narrow band gap,and because of its faster response time and higher electron mobility,it has become a popular research material for mid-wave infrared detectors.Now try to use magnetron sputtering to prepare In As Sb uncooled infrared detectors,and use CVD prepared graphene to construct PGN heterojunction devices.Later,in order to explore the application of graphene in wide bandgap devices,an attempt was made to construct a graphene/β-Ga₂O₃ photodiode.In this thesis,In As Sb andβ-Ga₂O₃ thin films were prepared by radio frequency（RF）magnetron sputtering,and then the optical,electrical,and structural properties were optimized.Use X-ray diffractometer（XRD）,scanning electron microscope（SEM）,transmission electron microscope（TEM）,atomic force microscope（AFM）,Leika optical microscope to observe its structural characteristics and surface morphology;UV-Vis absorption and transmission spectrometer,pull Mann spectrometer and Fourier infrared spectrometer（FTIR）observe its optical characteristics.And Keithley 2400 test system carried out corresponding characterization analysis on the prepared materialsand devices.The main content and conclusions of the thesis research are as follows:1.The preparation and characterization of In As Sb and the construction of In As Sb/Graphene/n-Si PGN heterojunction detector:The method of RF magnetron sputtering and the method of controlled variables were used to explore the In As Sb at different substrate temperatures and at different annealing temperaturesThe film was then optimized through characterization and electrical property analysis.It is found that the crystalline quality of the In As Sb film is improved after optimizing the substrate temperature and annealing at 500°C.The calculated optical band gap values are 0.24 e V and 0.11 e V before and after annealing,which are close to the theoretical value of 0.1-0.4 e V.By adding a single-layer graphene prepared by CVD between In As Sb and n-Si,the contact problem between the In As Sb film prepared by magnetron sputtering and n-Si is improved.Construct In As Sb/Graphene/n-Si PGN heterojunction detector.The comparison shows that the maximum response rate of the PGN device can reach 0.38 A/W（under 2V bias）,and the maximum detection rate can reach 8.6×109Jones（under-2V bias）.By comparison,after the graphene layer is introduced into the device,the response rate can be increased by 4 times,and the detection rate can be increased by about 8 times.In As Sb layers（87 nm,750 nm）with different thicknesses were prepared to optimize the device.The study found that In As Sb with a thickness of87 nm has the best improvement effect after adding graphene.It shows that the heterojunction of graphene and In As Sb needs to have a certain thickness in order to exert excellent performance.2.Preparation and characterization ofβ-Ga₂O₃ and construction ofβ-Ga₂O₃/Graphene photodiodes:Ga₂O₃ films with different parameters were also prepared by magnetron sputtering,and then the structure and optical methods of the films were optimized by characterization and comparison analysis.It is found that theβ-Ga₂O₃ film after optimizing the experimental parameters has been annealed at 900°C and the Ga₂O₃basically completely forms theβphase,and in the absorption test,it has good absorption characteristics for the 190-300 nm deep ultraviolet（DUV）light source.The gap is also very close to the theoretical value（4.9 e V）,about 4.89 e V.Based on the above optimizedβ-Ga₂O₃ film and graphene,three device structures were designed.After electrical performance testing,a vertical structure was finally selected as the device structure andβ-Ga₂O₃/Graphene photodiodes were successfully fabricated.The IV test shows that it has high rectification characteristics and low dark current,and the device can work under a higher bias voltage.