The Research On Room-temperature Terahertz Detector Based On Two-dimensional Material Heterojunction

Devices that are capable of detecting radiation in the terahertz part of the spectrum have potential applications in security check,biomedicine,and non-invasive quality inspection due to their unique optoelectronic properties.However,traditional photodetectors such as bolometer,Golay-cell,Schottky diode suffer from considerable drawbacks in terms of speed,working temperature and bulky,which impede their usage in smart,flexible communication or imaging system.Developing low-dimensional materials with peculiar electronic and optoelectronic properties provides the development of novel detectors make use of different light-induced effects.The advent of the semimetal-based topological phase of matter provides feasibility for the technological innovation of terahertz photodetectors for overcoming above drawbacks.In this work,a device based on Ni Te₂-graphene van der Waals heterostructure has been developed to inhibit the dark current and thermal-agitation noise and is capable of terahertz detection at room-temperature.Rivals with commercially thermal-based photodetectors,our device has already shown capabilities of large-area imaging,fast speed as well as high signal-to-noise ratio,can be rendered as an important step for exploring topological semimetal optoelectronics.The specific research contents achievements are as follows:1.The photocurrent is measured and analyzed at 0.02-0.04?0.08-0.12 and 0.24-0.30 THz respectively by using phase-locked technology,and the peak of photocurrent appeared at 0.03,0.09 and 0.28 THz,which is 37,2.5 and 1.2?A respectively.At the same time,the terahertz optical power incident on the device surface is calibrated at 0.28 THz,which is about 1m W·cm^-2,and the responsivity is calculated at 1.31A·W^-1.The oscilloscope recorded the response time of the device in one cycle,and the rise and fall response times were 13.5 and 13.7?s respectively.By measuring the dark current flowing through the device when the modulation frequency is 1k Hz,the equivalent noise power is calculated and analyzed,which is about 17.56pw·Hz-1/2.The effect of heterojunction on suppressing the dark current is verified.2.A terahertz active imaging system is built,and the prospect of the device in practical imaging application is verified by using the method of unit device scanning transmission imaging.The terahertz source emits terahertz wave at 0.28 THz,terahertz light is gathered through the lens to image the character"SITP"made of copper tape fixed on the two-dimensional mobile platform.The two-dimensional mobile platform transmits the received signal back to the computer control software Labview and obtains a high-resolution image through normalization analysis.