Study On Key Technologies Of Terahertz Detectors Based On Graphene Nanostructure

Terahertz(THz)usually refers to the electromagnetic wave with the wave frequency in 0.1 THz between 10 THz and it possesses many unique characteristics that are different from the microwave,infrared light and X-ray.THz has a wide application prospect in military radar,electronic warfare,communications,electromagnetic weapons,astronomy,safety inspection,medical imaging and nondestructive testing etc.At present,there are many deficiencies in the use of THz detector in terms of temperature,volume,response speed and so on,which has become a main restriction for the wide application of terahertz technology.Therefore,a new type of high sensitivity,fast response,working at room temperature,miniaturized,portable terahertz detector has become one of the hot spots around the world.Based on the excellent optical properties of graphene,a THz detector based on graphene nanomeshes(GNMs)was proposed.We designed THz photoelectric detector and studied the key technologies in the process,and especially,we focus on processing technology of nanoscale GNMs so as to lay the foundation for high-sensitivity GNMs THz photoelectric detector working at room temperature.The main contents are as follows:(1)Based on the analysis of the research status and development trend of terahertz detectors,and from the point of view of optoelectronic materials,the research on GNMs terahertz detectors was presented.(2)On the basis of the basic principle of graphene-based THz detector,based on the carrier continuity equation and Poisson equation and taking the carrier mobility,diffusion,generation,composite behavior into consideration,we established the mathematical model of GNMs THz detector.The electronic structure of GNMs was simulated by the ATK software.Furthermore,the p-i-n type THz detector was simulated by Comsol software,and the effects of length of i-section and geometric dimensions on the response current of the device were studied,which further optimized the device.(3)We designed the fabrication process of the GNMs THz detector and completed the process layout design.Graphene was synthesized by chemical vapor deposition(CVD)and then was transferred to SiO2/Si substrate by wet transfer method;The graphene nanomeshes were processed by electron beam lithography and oxygen plasma etching,and the key technology was studied.And GNMs THz detector sample was fabricated.(4)The transfer characteristics and output characteristics of the device were further analyzed,which showed that GNMs exhibited semiconducting properties,and the conductive properties of GNMs channel can regulated by changing the gate voltage.Additionally,the optical test platform was built to measure the optical current on GNMs THz photoelectric detector,and the imaging test of the key sample is successfully realized by using the detector.