Electrodeposition of copper-doped SnS thin films and their electric transmission properties control for thermoelectric enhancement

The thermoelectric performances of SnS are gradually noticed because of its structure similarity to SnSe which has the highest known thermoelectric performance. But the low electric transmission properties of SnS confines its thermoelectric performances. In this paper, we prepared Cu-doped SnS thin films with electrodeposition method. The Cu-doping content of the thin films were controlled by the adjustment of the electrolyte composition. The Cu doping narrowed the band gap of the SnS thin films, so that it promoted the carrier concentration of the films. The largest carrier concentration increased from 4.26 × 10¹⁵ to 436.42 × 10¹⁵ cm⁻³ after the Cu doping. By the additives in the electrolyte, the texture orientation and its coefficient were successfully controlled. The texture of (040) and (200) were obtained by the addition of urea and CTAB, respectively. The carrier mobility of the Cu-doped SnS thin films increased from 0.63 to 1.94 cm²/V s by the (200) texture. With a sample electrodeposition method, we successfully accomplished the combination of the Cu-doping and texture control of SnS thin films. Such a combination decreased the resistivity of the Cu-doped thin film with (200) texture from 322.53 to 24.50 Ω cm, so it was an effective path to improve the electric transmission performance of SnS thin films. Our results provide an easy method and a new view to improve the electric transmission performance of thermoelectric thin films.