Research On Topological Materials Terahertz Detection

The development of terahertz science and technology is limited by efficient terahertz sources and terahertz detectors.Two-dimensional materials represented by graphene,black phosphorus,and transition metal disulfides cannot achieve fast-response photoelectric detection in the terahertz band due to the lack of an optimal combination between band gap,dark current,and absorption capability.Emerging topological materials offer new avenues for optoelectronics research with nonlinear band transport,which makes advanced optoelectronic devices operating at longer wavelengths newly feasible.Specifically,platinum ditelluride（PtTe₂）has its special band structure with topologically protected electronic states,high carrier mobility and environmental stability advantages that allow it to be used in terahertz detection.Translated with www.Deep L.com/Translator（free version）This thesis focuses on the energy band properties of the topological material PtTe₂and its terahertz photoelectric response properties.The energy band structure and surface states of PtTe₂are investigated using first-principles calculations and Wannier functions;the terahertz photoelectric response of PtTe₂is investigated using Raman spectroscopy,micro and nano processing processes,semiconductor parameter testers,and terahertz photoelectric response systems.The main research contents and results of this paper are as follows.1.First-principles calculations of the topological material PtTe₂.In this part,we obtained the energy band structure of PtTe₂with or without considering the spin-orbit coupling effect based on the calculation,and confirmed after comparison that PtTe₂has a strong spin-orbit coupling effect,which cannot be neglected in the subsequent calculation;then we calculated the fractional wave density of states of PtTe₂,and confirmed that the energy band structure near its Dirac point is mainly contributed by the outer 5p orbitals of the Te element,and the 5p orbitals The evolutionary analysis of the Dirac point formation is carried out;finally,the surface state calculation of the（001）surface of PtTe₂using the Wannier function further confirms its Dirac point formation process and topological conservation properties.2.Terahertz photodetection study of topological material PtTe₂.The terahertz photodetector of PtTe₂based on log-periodic antenna was prepared by using micro and nano processing process,and the electrical characteristics were studied by semiconductor parameter tester,and the gate non-adjustable characteristics were found;by the terahertz photodetector system,the device has obvious optical response to terahertz,and the responsiveness of 3.85 A/W was achieved at room temperature,and the equivalent noise power was about 4.81 p W/Hz^1/2,which provides an opportunity to explore room-temperature high response optoelectronic devices based on topological materials and shows its wide application prospects in the low-energy especially terahertz band.