A study of bismuth sulphoselenide thin films: growth from the solution andproperties

Bismuth sulphoselenide [Bi-2(S,Se)(3)] thin films were obtained onto the th oroughly cleaned amorphous glass substrates using a simple chemical growth process. The basic ingredients used were analytical grade and a selenium so urce was obtained from a reflux action of the sodium sulphite with the meta l selenium. Growth kinetics and mechanism of film formation were studied fo r these films and are explained in brief. The compositional analysis was ca rried out to determine the actual contents of Bi3+ and Se2- in the films ta ken out of the bath. The X-ray diffraction analysis showed microcrystalline nature of the samples. It further revealed that the bismuth sulphoselenide is a ternary mixed chalcogenide having a chemical formula [Bi-2(S,Se)(3)]. Optical studies showed direct transitions for these films with a band gap of 1.9 eV for Bi2S3 and 0.97 eV for Bi2Se3. Thermoelectric power measuremen ts were performed on the [Bi-2(S,Se)(3)] films and showed n-type conduction . (C) 2000 Elsevier Science S.A. All rights reserved.