Growth And Photoelectric Properties Of SiC Based Graphene And Organic Thin Films

Graphene has important applications in the field of photodetectors due to its ultra-high carrier mobility,low carrier concentration,and wide spectral response from ultraviolet to near infrared.SiC epitaxial graphene,as a main method for the industrial production of highquality graphene,has the advantages of high compatibility with traditional Si processes,no transfer,and the continuation of many excellent properties of graphene.The position of the valence band forms a band gap of about 0.26 e V.In recent years,the appearance of van der Waals heterojunctions based on graphene materials has provided a new way for the study of low-dimensional materials.Organic semiconductors have been applied in the field of thin film transistors due to their advantages such as flexibility,ease of processing,and controllability.The formation of heterojunctions between graphene and organic semiconductors through van der Waals interaction is a new research direction in recent years,and offers more options for the development of photodetectors.However,in the currently reported heterojunction systems composed of graphene and organic semiconductors,due to the limitation of the preparation method,mechanically peeled graphene is used to transfer to the insulating substrate,and the two-dimensional organic material pentacene or PTCDA deposition,there are few reports on the growth of organic materials on SiC epitaxial graphene.Based on the above analysis,this paper carried out research on the growth and application of SiC-graphene and organic thin films.The organic small molecule osmium tetracarboxylic dianhydride-PTCDA powder was selected as the source material.Van der Waals epitaxy was used to grow the PTCDA film and perform detailed characterization.On this basis,devices were prepared for photoelectric performance testing.The specific content of this paper is as follows.Introduce the theoretical basis and research development status of graphene and its heterojunction,and analyze the theoretical support of growing new SiC / EG / PTCDA heterojunction.The key process flow of SiC thermal decomposition of graphene and Vanderbilt epitaxial PTCDA on EG was expounded,and a continuous graphene film and a 10 nm thick organic film were obtained.The grown material was characterized by various means,and it was found that the deposition of PTCDA enhanced the fluorescent properties of the heterogeneous system;the temperature control can induce the phase composition and grain size of the PTCDA film;the deposition of PTCDA makes the work function of graphene Increased by about 0.18 e V.Designed and prepared SiC / EG and SiC / EG / PTCDA two structure MSM lateral photodetectors,measured the dark current of SiC / EG / PTCDA device compared with SiC / EG reduced from 8.8m A to 6.2m A,verified UPS test result.The optical response of devices with different channel lengths was tested under 405 nm visible light and 365 nm ultraviolet light,respectively.The SiC / EG device and SiC / EG / PTCDA device were obtained under 60 m W optical power,10 um channel length,and 1.5V bias voltage.The responsivity to 405 nm visible light is 12.5m A / W and 1.8m A / W respectively,and the responsivity to 365 nm ultraviolet laser is 8.6m A / W and 12.3m A / W respectively.The response mechanism of the two devices and the deposition of PTCDA are analyzed.The impact of the response process.In order to reduce the thermal effect of ultraviolet laser radiation,changing the light source obtained a responsivity of not less than 28.7 m A / W.