Research On Terahertz Detector Based On 2D Charge Density Wave Material 1T-TaS₂

Terahertz wave is a very important electromagnetic wave wavelength in the electromagnetic spectrum.It has important application prospects in various fields such as physics,material science,life science,astronomy,information technology and national defense technology.For a long time,due to the lack of effective terahertz generation and detection methods,people lacked understanding of the characteristics of terahertz waves,forming the so-called"terahertz gap".The terahertz detector is the core component of the terahertz detection system,and its function is to convert the terahertz signal into an electrical signal,thereby detecting the information of the terahertz wave.Exploring room temperature terahertz detectors with high sensitivity,broad spectrum response,and fast response is the long-term goal of the development of terahertz detection technology.In recent years,with the rise of two-dimensional materials such as graphene,black phosphorus,and transition metal sulfides TMDCs,it has provided unlimited possibilities for exploring new photodetectors.The collective electronic state of the charge density wave（CDW）in the two-dimensional TMDCs material 1T-Ta S₂ has good electro-optical control characteristics.The use of external plane voltage and optical radiation can realize the switching of different CDW phases.The switching of the conductance during the phase change process is expected to realize enhanced detector response.Based on this,we explored the application of terahertz wave induced near commensurate charge density wave（NCCDW）and incommensurate charge density wave（ICCDW）phase transitions of 1T-Ta S₂ in the detection of terahertz at room temperature under an applied plane voltage.Using ultra-violet lithography,metal coating and other micro-nano device processing technologies,a 1T-Ta S₂ terahertz detector with two ends coupled with a butterfly antenna was constructed.In the photocurrent test in the 0.3 THz frequency band,the 1T-Ta S₂ terahertz detector achieved a room temperature current response rate of 180 A/W.The terahertz light response test results show that the 1T-Ta S₂CDW system is highly sensitive to terahertz light,and the enhancement of the response near the phase transition threshold voltage comes from the NCCDW-ICCDW phase transition induced by the terahertz wave.In addition,in view of the low response rate of the single-component 1T-Ta S₂ detector under no bias voltage,we propose a scheme to improve the performance of the detector by constructing a heterojunction.The 1T-Ta S₂/graphene heterojunction terahertz detector was constructed by two-dimensional material transfer technology,and the response enhancement under no bias voltage was realized.Finally,using the built terahertz imaging system,we used the 1T-Ta S₂/graphene heterojunction detector to perform terahertz imaging applications on different objects,and obtained good imaging results.Our research shows that 1T-Ta S₂ and its heterojunction detectors have good development prospects and important exploration value in exploring uncooled,highly sensitive terahertz detectors.