Research On Controllable Preparation Method Of Low-dimensional Carbon Material And Its Field Effect Transistor

As one of the largest materials families,carbon materials are gradually affecting the development direction of human technology.Many studies have shown that low dimensional carbon materials such as graphene,carbon nanotubes and graphene nanoribbons have outstanding properties.For the electrical property,graphene nanoribbon and carbon nanotube have been regarded as potential candidates of the"post-silicon era"because of their one-dimensional carbon skeleton structure,which exhibit far more excellent electrical properties than conventional silicon materials.However,these low-dimensional carbon materials still face many problems which need to be solved.For graphene nanoribbons,one of the biggest challenges is to find a high quality,large-scale controlled preparation method,which is an unavoidable problem in the process of realizing the application of graphene nano-ribbons to circuit.In order to solve these problemst,we mainly presented the preparation method of a highly controllable and large-scale aligned array of graphene nanoribbons Firstly,the overall idea of preparing graphene nanoribbon arrays based on the top-down principle is determined.We first optimized the transfer method for graphene with a new copper etchant,the graphene film is cleaned in the process of copper etching,and the ultraclean graphene films are obtained.The bad influence of contamination on graphene to the preparation of nanoribbon arrays is eliminated greatly.Next,according to the principle that the wrinkle on graphene surface is a folded multilayer structure,we furtherly determined the"self-mask"scheme using the wrinkle itself as the etching mask to refine the preparation of graphene nanoribbons into the exploration of graphene wrinkle preparation and etching conditions.By characterizing the wrinkles introduced by the array structure with different parameters,the optimal parameter range for preparing the wrinkle array was determined.Subsequently,we determined the appropriate etching parameters for graphene through experiments and etched graphene with wrinkled arrays.Raman spectrum and atomic force microscopy showed that we successfully fabricated graphene nanoribbon with a width of 10 nm as well as its parallel arrays.Furthermore,we found the limitations of the existing array structure,and optimized the structure so as to break through the fold density limit of the originalarray structure,the minimum spacing was reduced to 150 nm with a length of 300nm and the maximum density was increased to 6.7/μm.Finally,we used single graphene nanoribbons and nanoribbons arrays to prepare field-effect transistor devices.The electrical characterization results showed that the devices with an on-off ratio of current more than 10,and the significantly increased on-off ratio confirmed the successful preparation of graphene nanoribbon and their arrays..We also extracted the main parameters of the GNR array transistor,including a threshold voltage of 27.03 V,a carrier mobility of 33.8 cm~2/Vs.These performances were able to meet the requirements for the common field effect transistor devices completely.