Basic Physical Properties Of Tellurium Nanoflakes

Tellurium is the fifth group ? A element.It has the strongest electric Among all non-metallic elements,with a good thermal conductivity.Tellurium is a narrow band gap semiconductor material with an indirect band gap of 0.35 e V.Unlike ordinary twodimensional materials,tellurium have a unique one-dimensional van der Waals structure.The molecular chains are connected by van der Waals forces,stacked to form a sheet material,and there are no hanging bonds on the surface.The nanoflakes can be synthesized by chemical methods.Studies have shown that this material has a very high carrier mobility.At present,full-infrared photoelectric detector of tellurium nanomaterial devices has been achieved.And has achieved air stability full infrared photoelectric detection device.Demonstrates its great research value.Now,domestic researches on tellurium mainly focus on the electrical transport properties of tellurium nanowires.There are few reports on tellurium nanoflakes.In order to further explore the application and Structural properties of elemental tellurium nanoflakes.This experiment will study the basic physical properties of elemental tellurium nanoflakes.The results are as follows:In our experiment,we use hydrothermal method to synthesis tellurium nanoflakes.The samples are mainly trapezoidal,with a size of more than 10 ?m and the thickness is about 40 nm.This scale is in the research scope of mesoscopic.Raman spectroscopy measurements show that there are three modes of molecular vibration.Among them,in the direction perpendicular to the molecular chain has the strongest Raman peak.X-ray diffraction shows that the crystal structure is hexagonal.We use micro-nano structure processing technology to achieve field effect tube and Hall electrode.In the field effect tube measurement,the material exhibits p-type hole properties.And gate voltage can control the carrier.It shows that the drain current increases when the gate voltage is negative.And decreases when the gate voltage is positive.We studied the transport characteristics of tellurium nanoflakes.Which shown that tellurium nanodevices behave as metal-semiconductor transitions with decreasing temperature.And magnetic field can increase the materials band gap,result in the metalsemiconductor transition move to a high temperature region.In the magnetic transport measurement,it was found that the Hall resistivity increased continuously with the increase of the magnetic field.The carrier type is hole.In the magnetic field range of-4 T to 4 T,the Hall resistivity exhibits a good linear relationship.Through single-band fitting,the carrier density exceeds 1019 cm^-3 and the carrier mobility is among 80-200 cm² V^-1 s^-1.In longitudinal resistivity aspect,the phenomenon of magnetoresistance was observed,which has a square relationship with the magnetic field under a weak magnetic field and a linear relationship with a strong magnetic field.And when the temperature is lower than 12 K,it is observed that the tellurium has a localized negative magnetoresistance phenomenon under the weak magnetic field.We fit this weak antilocalization phenomenon through HLN?Hikami-Larkin-Nagaoka?formula?We found that with the temperature increases,the phase coherence length and temperature have a negative power exponential relationship,and the index is-0.5.It reveals that the tellurium nanosheet shows two-dimensional characteristics when a vertical magnetic field is applied.It is further shown that the scattering of materials at low temperature is mainly coherent scattering,and at high temperatures is mainly the effect of spin-orbit coupling and elastic scattering.