Tailoring optoelectronic properties of earth abundant ZnSnN2 by combinatorial RF magnetron sputtering

Zn-IV-N-2 semiconductors are often considered as imminent materials alternative to InGaN and requisite thin film photovoltaic absorber materials for light harvesting due to its direct band gap, steep absorption onset and disorder-driven band gap tenability. In view of this, ZnSnN2 thin films were successfully prepared by reactive RF magnetron co-sputtering with different Sn concentrations at 450 degrees C substrate temperature. The films grown at 450 degrees C with different Sn target power were found to be orthorhombic crystal structure which has higher grain size (13-28 nm), low carrier density (-4.99 x 10(18) to -7.01 x 10(17) cm(-3)) and the maximum mobility (11.1 to 15.5 cm(2) V-1 s(-1)). The phase purity and chemical bonding states of ZnSnN2 were investigated by XPS analysis. Vibrational modes of ZnSnN2 confirmed the presence of N-bonding with Zn and Sn. The optical band gap decreased from 1.96 to 1.77 eV as the Sn power increased. Hence, it is suggested that ZnSnN2 thin film grown under this technique could be utilized as efficient absorber layer in thin film solar cells due to the astonishing optical and electrical properties. (C) 2018 Elsevier B.V. All rights reserved.