Study On Photoelectric Properties Of Low Dimensional Te And MoS₂ Nanoscrolls

Tellurium is a member VIA element in the fifth period.It has many excellent properties,including environmental stability,piezoelectric effect,high carrier mobility and light responsivity.Tellurium is a narrow band gap semiconductor,and the size of the band gap is related to the thickness,ranging from a single layer to a bulk material of 0.35 to 1.04 e V.Single crystal tellurium is composed of a unique one-dimensional chain structure.The chains are combined by van der Waals force and stacked to form layered materials without surface dangling bonds.In recent years,the self-assembled structure of atomic-level thin transition metal chalcogenide(TMDCs)films has become an emerging field in optoelectronic physics and device research.As a member of transition metal chalcogenide compounds,molybdenum disulfide(MoS₂)has the advantages of atomic-level thickness,good environmental stability,adjustable band gap,and ultra-high carrier mobility.According to related reports on molybdenum disulfide nanoscrolls,it is found that compared with molybdenum disulfide thin films,it has more excellent photoelectric properties,so molybdenum disulfide nanoscrolls have potential application prospects in memory,photodetectors,memristors,etc.The electrical transport and photoelectric properties of elemental tellurium with a one-dimensional chain structure are studied in this paper.In addition,a device based on molybdenum disulfide nanoscrolls was prepared and its electrical and optical properties were preliminarily discussed.The main work of this paper includes:(1)Preparation of single crystal tellurium by physical vapor deposition method in the experiment and its properties were basically characterized.The prepared samples were mainly trapezoidal and rod-shaped and the length exceeded 50um.The material has three Raman vibration modes,E₁,A₁,and E₂.The vibration mode A₁ in the direction perpendicular to the molecular chain has the strongest peak.X-ray diffraction results show that the prepared material is single crystal tellurium of hexagonal crystal system.It can be seen from the electrical test results that the material is a p-type semiconductor and the semiconductor is found to be transformed into metallic properties as the temperature decreases.(2)In the experiment,by preparing suspended samples,performing variable temperature Raman test and variable power Raman test on the samples,the first-order temperature coefficient and the relationship between the phonon frequency and temperature are obtained,and the calculated thermal conductivity is 1.496 W/(m·K),close to related literature reports.(3)In the experiment,a single layer of MoS₂ and MoS₂ nanoscrolls were prepared by chemical vapor deposition method,and the basic properties of the material were characterized.The grown samples are mainly equilateral triangles with a size of up to50um and a thickness of 1nm.The research results obtained the influence of temperature field change on the phonon vibration characteristics of single-layer MoS₂and MoS₂ nanoscrolls.