Research On Bismuth Selenide And Composite Structure Optoelectronic Devices

Topological insulators,represented by bismuth selenide（Bi₂Se₃）,are a new type of semiconductor material with a special electronic state,which has attracted extensive attention from researchers in recent years.The current research on bismuth selenide materials is mainly focused on the physical properties of the film after growth,such as growth shape,carrier mobility,and electronic state,etc.The application of thin film materials to optoelectronic devices is still in the development stage and is also one of the current research hotspots.In this thesis,bismuth selenide films are grown on different target substrates,and photodetectors with wide-band detection capabilities（visible light to mid-infrared）are prepared.First,the controllable preparation and characterization of bismuth selenide thin films were studied,and then the photoelectric response characteristics of bismuth selenide/silicon heterojunction photodetectors were tested and analyzed.Finally,the photoelectric properties of bismuth selenide and its composite structure photoelectric devices were studied.The main research contents are:1.Preparation and characterization of bismuth selenide film.Different shapes of bismuth selenide films were grown by tube furnace vapor deposition,the gas flux,growth temperature and the quality of the bismuth selenide source were adjusted to improve the film-forming environment of the material,thereby obtaining a bismuth selenide film with uniform texture.Then through scanning electron microscope（SEM）,Raman spectrometer（Raman Spectrometer）,X-ray diffractometer（XRD）,atomic force microscope（AFM）,Hall effect tester（Hall effect tester）and other equipment on the surface of the bismuth selenide film The morphology and structure were characterized and simply analyzed.2.Preparation and performance test of bismuth selenide/silicon heterojunction photodetector.The bismuth selenide film is directly grown on the etched silicon/silicon dioxide window substrate,and then made into a bismuth selenide/silicon heterojunction photodetector,and the photoelectric response of the device in the visible light band to the mid-infrared band is measured Tested.Using a 635 nm laser,when the incident power is150μW,the responsivity and specific detection rate are 31.13 m A/W and 5.81×10¹¹Jones,respectively.Using a 1550 nm laser,when the incident power is 100 m W,the responsivity and specific detection rate are 1.5×10^-4m A/W and 1.95×10⁶Jones,respectively.Using a2700 nm laser,when the incident power is 10 m W,the responsivity and specific detection rate are 2.5×10^-4m A/W and 1.93×10⁶Jones,respectively.The results indicate that the bismuth selenide/silicon heterojunction detector has the best photoelectric response in the visible light band,and has a good photoelectric response in the near-infrared and mid-infrared bands,so it is suitable for wide-band detection.3.Finally,bismuth selenide and its composite structure optoelectronic devices were manufactured.A photodetector with a bismuth selenide/micropyramid silicon composite structure was prepared,and the responsivity tested at the 635nm band was 45.5m A/W,and the normalized detection rate was about 7.67×10¹¹Jones,which was better than under the same conditions.The photoelectric response of the bismuth selenide/silicon photodetector is better.The results show that by using a wet etching process to fabricate pyramid microstructures on the surface of a silicon substrate,the silicon substrate with a composite structure can effectively enhance light absorption,thereby improving the photoelectric detection performance.