Two-dimensional Material Terahertz Detector And Its Photoelectric Properties

Terahertz radiation?THz radiation?is a very important band,which has wide application prospects,so it has attracted wide attention.Terahertz?THz?detection technology is a significant field of terahertz technology.Fabrication of terahertz detectors with room temperature operation,fast response,high detection sensitivity and large-scale array integration is the main development direction of terahertz detection technology.The rapid development of two-dimensional materials provides new candidates in materials and methods for terahertz detection.In recent years,the properties of two-dimensional transition metal sulfides?TMDCs?have made remarkable achievements and injected new vitality into terahertz detection.However,the existing terahertz detectors still have some problems,such as low detection efficiency,long response time and complex process.Solving these problems is a hot topic in the field of terahertz detection.In this paper,terahertz detectors based on two-dimensional materials are mainly studied.They include the use of the logarithmic antenna and the butterfly antenna to couple terahertz waves,fabricating terahertz detectors based on 2H-TaSe₂ under room temperature and low temperature.The device performance is improved by antenna coupling,electrical modulation and exploring new mechanisms.This terahertz detector has the advantages of simple process,compatibility with silicon-based semiconductor technology,easy regulation,batch production,and its performance is in the forefront of similar devices,which provides a new idea and method for the current two-dimensional material terahertz detection technology.The main innovations of this paper are presented as follows:1.In order to realize terahertz detectors with high responsivity,we have fabricated integrated charge density wave?CDW?terahertz detectors for nano antennas.The2H-TaSe₂ was transferred to Si/SiO₂ substrates by mechanical exfoliated.The Cr/Au micro-nanostructures and source-drain electrodes were fabricated by ultraviolet lithography and hot-evaporation.The collective drive of unbalanced carriers in field effect transistors?FETs?induced by CDW is used to detect sensitive light in high tracking terahertz band.The photodetector based on 2H-TaSe₂ has a fast response up to 14?s and a responsivity over 27 V/W at room temperature.It can be controlled electrically and optically by the top gate.In order to reduce the dark current and noise of the device,we also fabricated graphene-2H-TaSe₂ heterojunction photodetector.Its responsivity was doubled compared with the 2H-TaSe₂ photodetector.The rapid response time,relatively high responsivity and easy fabrication of these devices have created new prospects for exploring CDW condensates in TMDCs in order to overcome the limitations of various practical applications within the THz spectrum.2.By designing the butterfly antenna,we fabricated the terahertz detector and tested it under low temperature.Through observing the resistance and photocurrent of the device during the phase transition process,the collective excitation of the CDW state and the mode of collective current transmission are explored.The results show that the device has good detection performance and great application space.It is one of the candidates for two-dimensional terahertz detection technology under room temperature and even under low temperature.3.Use self-built optical platform to focus terahertz wave and point-by-point scanning method to image objects in continuous wave.The advantage of Thz continuous imaging system is that the system configuration is simple and the cost is low,which is easy to be used in a wide range.By analyzing the intensity information collected from transmission terahertz imaging of rings,blades and glue,it can be further improved.We hope that terahertz large area array imaging will be realized in the near future.