Inducing a level inside of CdTe bandgap doping with Sn using a co-sublimation technique by CSS

In this work, cadmium telluride (CdTe) thin films were doped with Sn using a low-cost co-sublimation technique by a homemade close-spaced sublimation (CSS) system. Sn amount was calculated to obtain CdTe film doped with a percentage content lower than 0.4 at%. Chemical, structural, morphological, and optical properties of the as-deposited CdTe (u-CdTe) and Sn-doped CdTe (t-CdTe) films were measured and compared. Raman and XPS characterization showed the presence of Sn in t-CdTe thin films and XRD analysis revealed a strong signal related to CdTe planes (220) and (311) and in a lesser extent a signal related to SnTe. Irregular shaped grains with similar size related to Sn incorporation in the films were found with FE-SEM technique. Photoluminescence spectrum indicates an energy band at 0.7 eV, generating a band inside of CdTe bandgap, due to defects induced by the Sn in CdTe lattice, matching with a theoretical study. The changes observed in Sn doped CdTe film suggest that it can be used for optoelectronics applications. •A close-spaced sublimation system was developed to incorporate Sn in CdTe film.•Sn was successfully integrated into the CdTe lattice.•Photoluminescence spectrum shows an intense band inside of the CdTe bandgap.•The results are in good agreement with a theoretical study of Sn-doped CdTe.