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

Abstract

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.