Preparation Of Graphene By CVD And Its Applicaton In Terahertz Detectors

Graphene is a photoelectric two-dimensional material with many excellent characteristics.Its excellent properties such as high mechanical strength,high thermal conductivity,high specific surface area and high electron mobility make it show great application prospects in terahertz detectors.But how to prepare and transfer high-quality graphene is the key to restrict the high-performance application in terahertz detectors.This thesis focuses on the preparation and transfer of graphene by chemical vapor deposition,systematically studied the controllable preparation process of growing graphene by chemical vapor deposition,and analyzed the process environment to promote the growth of graphene through experiments;Improvement of copper etching transfer method and device was proposed;Finally,the application of graphene in the direction of terahertz detector was studied.The main research results are as follows:(1)The reliable preparation and transfer process of single crystal graphene by chemical vapor deposition was studied and obtained.Using copper foil as the substrate,the effects of growth temperature,gas flow rate and deposition time on the size and surface morphology of graphene single crystal were systematically studied.Based on the traditional copper etching transfer method,an improved device and method for wet transfer of graphene film is proposed,which improved the technology in the prior art that the transfer process is likely to cause graphene wrinkling or damage,and destroy the integrity of graphene Problem;By regulating the specific position of graphene transferred to the target substrate,to ensure that the graphene has good contact with the target substrate,the purpose of ensuring the quality of the transferred graphene was achieved.(2)Based on the graphene preparation technology,transfer method and device,the graphene was successfully transferred from the copper foil to the substrate.Graphene was characterized by an optical microscope and a laser confocal Raman tester.The optical microscope observed almost no damage at the center of the graphene;Raman spectroscopy showed that the graphene lattice had almost no defects and the transferred graphene was of good quality.(3)A graphene transistor and graphene terahertz detector were prepared.Based on the working principle of the graphene terahertz detector,a series of preparation processes for making the device structure and parameters were proposed,the device structure and process flow that meet the requirements were designed,and the detector layout design was completed using L-Edit software.The preparation of device was completed by the semiconductor technology.During the test,the unit can be arbitrarily selected for cutting and testing,indicating that the detector is feasible in the process.(4)The electrical test of graphene transistor and terahertz detector were completed.The transfer characteristic curve of the device and the Rtot-VBG curve fitting were completed using a semiconductor parameter analyzer,the performance of the device was analyzed,the Dirac point and mobility of the device were obtained,and the main factors limiting the mobility were summarized.