Study On Optical Field Regulatory And Detection Mechanism Of Infrared Terahertz Devices

Terahertz technology is an attractive area of research with great potential in semiconductors,medical,manufacturing,space and defense industries.Terahertz discipline research usually involves multiple disciplines such as optoelectronics,semiconductor physics,and materials science.In many applications of terahertz technology,terahertz detectors are the key link.In this paper,several terahertz devices based on potential material systems are studied.In combination with material growth,theoretical calculation,device manufacturing and photoelectric measurement,infrared terahertz detection based on tin diselenide（Sn Se₂）and palladium ditelluride（Pd Te₂）materials is studied.Based on the characterization and research of materials,different photoelectric coupling structures were designed to enhance the performance of THz devices.It also explores the detection mechanism of new materials and proves the excellent room-temperature detection capability of the device.The main innovations and research of this paper are as follows:1.The two-dimensional material Sn Se₂ has good thermal conductivity and high thermoelectric potential,and also has the advantage of low cost.In the research of Sn Se₂-based detectors,the focus is mainly on the visible and infrared bands,and it has never been extended to the terahertz band.Here,we first prepared a Sn Se₂ device through micro-nano processing to discuss its performance in visible infrared detection,and realized dual-band imaging.Next,we extended the working range of the Sn Se₂detector to the terahertz band,and shortened the device channel to 100 nm by obliquely metal vapor depositing.Theoretical simulation and experiment proved the enhancement of device performance.Taking advantage of the excellent thermoelectric properties of Sn Se₂,combined with the photo-thermoelectric effect,through the deposition of different metals on the contact electrode,the responsivity of the device is further improved,and the imaging in the terahertz band is realized.Experimental results show that the Sn Se₂-based device can work in the range of visible to terahertz.Especially in the terahertz band,excellent performance can be obtained,including fast response time（2.2μs）and high responsivity（170 V/W）,which has great potential in various electronic and optical applications.2.The appearance of topological Dirac semimetals provides an ideal experimental system for discovering new quasiparticles,which are often elusive in high-energy physics.Such materials have been predicted to have chiral-related transport characteristics and nonlinear optical phenomena,which will depend on the breaking of time or space inversion symmetry.At present,the experimental research of this kind of material in practical technology application is still insufficient.We studied the detection performance and photocurrent generation mechanism of room temperature terahertz detectors based on type-II Dirac semimetal Pd Te₂ material.Our experiments found that the synergistic effect of charge transfer and electric field localization near the metal-material interface resulted in a large second-order nonlinear photocurrent in the device.The results show that the Pd Te₂-based room-temperature terahertz detector can achieve a responsivity of 10 A/W and a noise equivalent power below 2 p W/Hz^0.5.Confirmed the potential of the device in light sensitive detection and large area rapid imaging.3.The type-II Dirac semimetal Pd Te₂-class material may be an ideal platform for terahertz technology.We further expand the terahertz detection of such devices,and study the polarization detection,anisotropic photocurrent,low-temperature response,device stability,and related heterojunction.The anisotropy of Pd Te₂ depends on the direction of the crystal,which produces photocurrent that depends on the polarization control.Due to its layered material properties,it is easier to form heterojunction devices with graphene.The results show that the Pd Te₂ device has high anisotropy,good stability,low-temperature enhanced light response,and easy preparation of heterojunction devices.These advantages provide new design concepts and creative ideas for new optoelectronic devices based on such materials,and are expected to promote the exploration of new optoelectronic phenomena.The research content and results of this paper provide an important research foundation for the exploration and realization of room temperature infrared terahertz detectors based on new materials.Explored and studied the detector based on two new materials,the thermoelectric material tin diselenide and the type-II Dirac semimetal material palladium ditelluride.This article starts from different terahertz detection mechanisms,including designing devices to enhance the thermoelectric effect,verifying the nonlinear detection mechanism of the type-II Dirac semimetal devices,and achieving competitive response performance and preliminary imaging applications.It provides a foundation for expanding more new materials that can be used for photoelectric detection and the diversified photoelectric applications of related devices.