Band structure of amorphous zinc tin oxide thin films deposited by atomic layer deposition

Recently, zinc tin oxide (ZTO) has attracted attention as an alternative buffer layer to replace CdS for photovoltaic cells. ZTO thin films were grown by atomic layer deposition from diethylzinc, tetrakis (dimethylamido)tin, and water. Compositional, structural and optical properties were characterized to construct band diagram of the ZTO films depending on Sn content. The ZTO films exhibit optical bandgaps of 2.95-3.07 eV which are wider than that of CdS. Furthermore, their work function is also observed to vary in a wide range of 4.32-5.16 eV. It is attributed to incorporation of Sn into ZTO which strongly influences formation of oxygen vacancies. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.