Fabrication of Bi_1-xSb_x thermoelectric semiconductor films by electrodeposition

Bi_1-xSb_x semiconductor alloy are important thermoelectric and magnetoelectronic materials, exhibiting unusual electronic properties, and are of interest for electric-cooling, thermal energy conversion, and magnetoelectronic devices. Electrochemical deposition is of simple and low cost method, displaying a potential application in the deposition of semiconductor films. The electrodeposition of Bi_1-xSb_x thermoelectric film from Bi and Sb chloride electrolyte with high concentration of chloride acid was investigated systematically. The concentration of Bi_1-xSb_x in solution was gradually changed from pure Bi to pure Sb. The structures of deposited films were investigated with electron microscopy (SEM, TEM), electron probe (WBS), and X ray diffraction method (XRD). The results shown that the high concentration of chloride acid of electrolyte was effective to avoid the tendency of formation of antimony oxide in the electrolyte, and high quality Bi_1-xSb_x films were electrodeposited across the entire composition range from pure Bi to pure Sb. The films present a textured crystal structure, with (012) preferred orientation, and the grain size also changed for different solution composition. The electrodeposition process is controlled by the solution diffusion. The potential gap between the deposition and the strip of the films varied with the change of solution composition, and process of deposition to stripping for antimony film is more unreversible than that for bismuth film.