Research On Graphene Field Effect Transistor Terahertz Detector

In the electromagnetic spectrum,the location of the terahertz wave is quite special.Because of its excellent properties,it has broad application prospects in the fields of security inspection,imaging,radar,communications,and biomedicine.With the rapid development of semiconductor materials and electronic technology,major breakthroughs have been made in the development and utilization of terahertz frequency bands.However,due to issues such as sensitivity and stability,the room temperature detection technology in the terahertz band is still immature.With the continuous development of terahertz technology,the requirements for compact,fast and sensitive terahertz detectors that operate at room temperature are getting higher and higher.Traditional terahertz photodetectors are mostly based on thermal sensing devices.Although they have high responsivity,they have slower response speed,higher noise,or lower operating temperature.The detection of terahertz in the field effect transistor is achieved by exciting the plasma wave in the channel of the transistor.The terahertz wave is coupled into the field-effect electronic channel by using an antenna,grating coupler or other means.The incident terahertz wave not only causes the oscillation of the charge density,but also causes the oscillation of the charge drift.Graphene is a two-dimensional material with a hexagonal honeycomb structure composed of carbon atoms through sp~2hybrid orbitals.Because of its unique photoelectric characteristics such as high mobility,adjustable band gap,and broadband absorption,it has great application potential in terahertz detection.In this paper,through structural design,graphene and field-effect transistors are combined to realize the detection of terahertz radiation,and the factors that affect the performance of graphene terahertz detectors are studied.The main work of this paper is as follows:(1)Analyze the carrier diffusion and transport model in the electron channel,and calculate the photovoltage of the terahertz response in the field effect transistor;(2)The field effect factor in the graphene field effect transistor terahertz detector is analyzed and calculated,and the relationship between the field effect factor and the gate voltage change is obtained;(3)A graphene field-effect transistor terahertz detector based on an antenna coupling structure is designed.The simulation results show that the detector can respond to terahertz radiation of different frequencies;(4)Analyze the influence of the structure size on the edge electric field distribution on both sides of the gate and the difference between the electric field intensity,optimize and adjust the structure parameters,and find the best size to improve the performance of the detector.