Research On Graphene FET Photoelectric Sensor

As a special device that converts measured physical quantities into electrical signals or other signals according to specific laws,sensors become peripheral nerves of the natural world and the electronic world.As an important branch of the sensor,the photoelectric sensor plays a central role in the applications of optical communication,imaging and detection,just as the eyes of the electronic system perceiving the external world.At present,the main sensor products in the market are limited in detection wavelength,low responsivity,and complex in structure.To solve these problems and practical needs,combined with the graphene's advantages of wide detection wavelength range,high responsivity,and high electron mobility,a graphene field effect transistors(FET)photoelectric sensor with a silicon nitride protective layer has been proposed.Its preparation process,environmental stability test,and its electrical characteristics and photoelectric response characteristics were studied and analyzed.The research results have potential application value.The main work of the thesis is as follows:1.The preparation process and measurement method of a graphene FET photoelectric sensor based on a Micro-Electro-Mechanical System(MEMS)were studied.Thus,a graphene heterojunction field effect transistor with silicon nitride(SiNx)double stress layer as a substrate,silicon dioxide(Si02)as a dielectric material,and graphene as a sensitive material is proposed,which is expected to solve the detection wavelength.2.In terms of process,the process principle and process steps of the graphene FET photoelectric sensor were studied.Under the existing experimental conditions,the device was prepared and the process steps were optimized,and the success rate of the device preparation was improved.Based on the preparation process of the planar graphene FET,the experiment of releasing stress of the stress layer to drive the planar graphene FET to self-assemble as a "microtube" type three-dimensional graphene FET has been performed successfully,laying the foundation for the preparation of highly integrated arrayed photodetectors3.Through optical microscopy,Scanning Electronic Microscopy(SEM),X-ray spectrum,Raman spectroscopy and other technical means to observe and test the prepared device,get its morphology characteristics and composition characteristics.The electrical properties of the device were tested by a semiconductor tester and the devices before and after deposition of a silicon nitride protective layer were compared and tested.4.Use a Raman laser,a terahertz laser generator and other instruments to build an optoelectronic test system.Photoelectric response detection and terahertz wave detection of different wavelengths were performed on the prepared graphene FET,and the test results were studied and analyzed.The test results show that the photoelectric sensor proposed in this paper has a wide detection band for detecting visible wavelength and terahertz wavelength,which solves the problem of narrower detection range of existing photoelectric sensors.In summary,the graphene FET photoelectric sensor proposed in this paper has many advantages such as wide detection wavelength range,high responsivity,good environmental stability,and easy preparation and integration.It provides new research ideas for MEMS photoelectric sensors and has a very broad application prospects.