Research On The Preparation Of Graphene-based Nanocomposite Structures And Their Photoelectric Response

Photodetectors,which could convert optical signals into electrical signals,play an important role in technology,production and daily life.With the continuous advancement of Moore's law,the development of the next generation of photodetector with smaller size,higher performance and more intelligent modulation becomes a more and more urgent need.Graphene discovered in 2004 is composed of a single layer of carbon atoms arranged in a honey-comb lattice.Because of its two-dimensional structure,ultrahigh mobility,wide absorption spectrum and tunability,graphene has been regarded as the most promising materials for the next generation of optoelectronic devices,and has great value for theoretical research and practical application.However,due to the low light absorption and short lifetime of carriers in graphene,the responsivity of photodetector using pristine graphene as the response material is very low.In recent years,in order to improve the light absorption and optoelectronic response of graphene,researchers have proposed a variety of strategies.Among them,graphene-based nanocomposite structures show great potential in the improvement of responsivity,response speed and response wavelength,and also have become a widely adopted method for the development of graphene-based photodetection devices.So far,the materials and structures used in graphene-based nanocomposite devices are diverse,but most of them have difficulty on giving consideration to the performances in responsivity,response speed and response waveband at the same time,and few researches are focusing on realizing simple and effective modulation on photoelectric response.Therefore,more efforts are needed to realize small,high performance and controllable graphene-based nanocomposite photodetector.In this paper,based on the excellent properties of graphene,and by means of improving structure,enhancing optoelectronic effects and composting new materials,we integrate graphene with silicon,gold nanofilm,superionic conductor film and quantum dots,and prepare“gold/graphene/silicon”nanocomposite photodetector,“superionic conductor Rb Ag₄I₅/graphene”nanocomposite transistor and“eutectic indium gallium alloy quantum dot/graphene”nanocomposite photodetector respectively.The photoelectric response performance and internal physical mechanism of three nanocomposite devices are systematically studied,and great process is made in enhancing absorption,improving photoelectric response and increasing controllability for photodetector.In the experiment,we have successfully prepared three kinds of nanocomposite devices,all of which can realize wideband detection from ultraviolet light to infrared light with high responsivity and fast response speed.In addition,by means of changing laser power and gate voltage,we have realized the regulation on the photocurrent polarity and amplitude.In the theory,by means of measurement characterization and theoretical modeling,we analyze enhancement and regulation mechanism in the three devices,and put forward the synergy mechanism of carrier density and mobility,the regulation mechanism of gate on the interaction between electron and ion,and enhancement mechanism of quantum dot with multilevel energy band structure,successfully explaining the experimental phenomena and fitting well with experimental data.The new-type graphene-based nanocomposite devices proposed in this paper,on the one hand,show good photoelectric performance and have good application value and potential;on the other hand,also provide a new reference and thought for the further development of graphene-based photodetector.