Optimization of Electrodeposited p‐Doped Sb₂Te₃ Thermoelectric Films by Millisecond Potentiostatic Pulses

Abstract

Abstract A systematic optimization of p‐type Sb 2 Te 3 thermoelectric films made by potentiostatic electrodeposition on Au and stainless steel substrates is presented. The influence of the preparative parameters of deposition voltage, concentration, and the deposition method are investigated in a nitric acid solution. As a postdeposition step, the influence of annealing the films is investigated. The use of a potential‐controlled millisecond‐pulsed deposition method could improve both the morphology and the composition of the films. The samples are characterized in terms of composition, crystallinity, Seebeck coefficient, and electrical resistivity. Pulsed‐deposited films exhibit Seebeck coefficients of up to 160 μV K −1 and an electrical conductivity of 280 S cm −1 at room temperature, resulting in power factors of about 700 μW m −1 K −2 . After annealing, power factors of maximum 852 μW m −1 K −2 are achieved. Although the annealing of DC‐deposited films significantly increased the power factor, they do not reach the values of the pulsed‐deposited films in the preannealing state. Structural analysis is performed with X‐ray diffraction and shows the crystalline structure of Sb 2 Te 3 films. The performance is tuned by annealing of deposited films up to 300 °C under He atmosphere while performing in‐situ X‐ray diffraction and resistivity measurements. The chemical analysis of the films is performed by inductively coupled plasma optical emission spectroscopy (ICP‐OES) as well as scanning electron microscope energy dispersive X‐ray analysis (SEM‐EDX).