Research On Preparation And Characteristics Of GeTe Thermoelectric Thin Film Materials

Recently,as a promising candidate for lead-free thermoelectric(TE)materials,GeTe has received extensive attention from the material science community.Using the characteristics of the low Seebeck coefficient and high thermal conductivity of GeTe materials at room temperature,this thesis carried out research on the thermoelectric characteristics of GeTe thermoelectric thin film preparation and doping modification.The thesis prepared GeTe thermoelectric thin films under different parameter conditions,and studied the effect of Al and Sb element doping on the thermoelectric properties of GeTe thin films through doping modification technology.The research results can be used for the preparation of future GeTe thermoelectric thin film materials and the improvement of energy conversion of GeTe thin film thermoelectric materials through doping modification technology.The main research work is as follows:(1)Using RF magnetron sputtering coating technology,under different sputtering power and deposition time,GeTe semiconductor thermoelectric thin film materials with different thicknesses are prepared,analyze and characterize the surface morphology,crystal structure,composition,etc.of the prepared samples using SEM,AFM,XRD,EDS and other analysis and detection equipment,and use self-made thermoelectric property test device and thermal conductivity tester to analyze their thermoelectric properties,The effect of annealing on the thermoelectric properties of the prepared samples was studied.The experimental results show that the single-crystal GeTe thin film prepared by magnetron sputtering coating method is a p-type semiconductor thermoelectric material,and its maximum Seebeck coefficient can reach 8.22 m V/K.Annealing helps to improve and increase the thermoelectric figure of the prepared sample.(2)Al/GeTe thermoelectric thin films with different doping levels were prepared by dual-target magnetron co-sputtering technology.The surface morphology of the sample was observed with SEM and EDS instruments respectively,the percentage of doping and the element composition of the thermoelectric film layer under different preparation conditions were determined,and the effects of different Al doping levels on the thermoelectric properties of GeTe thin film samples were analyzed.The experiment found that the Al element dissolved in the GeTe lattice can suppress the concentration of Ge vacancies in the lattice,resulting in a decrease in carrier concentration,which in turn increases the Seebeck coefficient.Comparisonof samples before and after annealing found that annealing treatment had a greater effect on the Seebeck coefficient of Al/GeTe thin film samples.(3)Sb/GeTe thermoelectric thin films with different doping amounts were prepared by dual-target magnetron co-sputtering technology.The surface morphology was observed with SEM and EDS instruments respectively,the percentage content and element composition of the thermoelectric film layer under different preparation conditions were determined,and the influence of different doping amounts of Sb element on the thermoelectric properties of GeTe thin film samples was analyzed.Studies have shown that the doping of Sb element can greatly improve the conductivity of GeTe materials,but the annealing treatment did not change the properties of Sb/GeTe thin film samples.Among the three groups of samples,the Sb/GeTe thin film samples have the largest ZT value and the best thermoelectric characteristics.