Study On Preparation And The Thermoelectric Transport Characteristics Of CoSb₃ Based Thermoelectric Thin Films

Thermoelectric material is one of environment-friendly and energy-saving materials,which can convert heat into electricity directly.It has important practical value and broadly prospect of applicration.The CoSb₃ based thermoelectric material is regarded as one of the most popular skutterudite materials in recent years.It has a large conductivity and moderate seebeck coefficient,so the CoSb₃ based thermoelectric material is considered to be one of the most widely used thermoelectric materials in the region of middle temperature.Relevant research indicates that the low dimensional or doped into thermoelectric materials is important to improve properties of CoSb₃ based thermoelectric materials.Therefore,in this paper,the high performance CoSb₃ thermoelectric thin films were preparated by magnetron co-sputtering technology.The influence of preparation technology and doped amount on the microstructure and thermoelectric transport properties of Co Sb₃ based thermoelectric thin films were researched.Furthermore,thermoelectric properties of CoSb₃ based thermoelectric thin films are enhanced by single element or multi-element doping.Firstly,high performance samples of CoSb₃ thermoelectric thin film were prepared by magnetron sputtering.The results show that the optimal sputtering power of the Co-Sb alloy target is 50W.With annealing process,samples of CoSb₃thermoelectric films can get a single crystal structure of CoSb₃,when prepared by the alloy target with Co,Sb atom content ratio of 1:3.5,and the best annealing temperature is 325?,and its biggest power factor can achieve to 2.27×10^-2mWm^-1K^-2.But,when prepared by the alloy target with Co,Sb atom content ratio of1:3.5,with a certain substrate temperature,the samples have obvious impurity phases.It also can get single skutterudite CoSb₃ structure,when the thin films prepared by the target with Co and Sb element ratio of 1:3,the best deposition substrate temperature is250?,and its biggest power factor can achieve to 9.75×10^-2 mWm^-1K^-2.Secondly,Ag single doped CoSb₃ based thermoelectric thin film samples with high thermoelectric properties were prepared,based on the optimal preparation parameters.The influence of the content of Ag on the thermoelectric properties was investigated.Results can be obtained,it is Ag doped in the lattice,and it is likely to fill in the gap of lattice cage.The seebeck coefficient,conductivity and power factor of the doped films were obviously enhanced.The thin film samples were prepared by using setting substrate temperature method,Ag doped amount for 0.3%of the thin film samples have the largest power factor,it is 0.29 mWm^-1K^-2.Lastly,based on the optimum parameters,using Sn?In or Ti?plating prefabricated layer with magnetron sputtering method,to explore the influence of CoSb₃ based thermoelectric film samples on thermoelectric performance.The research results show that when the Sn,Ti and In with Ag double doped,the electrical conductivity of CoSb₃ film samples is improved whether compared to undoped thin film samples or Ag doped thin film samples.When the doped thickness of Sn is 5 nm,the maximum power factor is 0.31 mWm^-1K^-2.