Optimizing the electrical transport properties of ZnSnO thin films by post growth annealing in air

Abstract

In this manuscript, we have successfully enhanced the thermoelectric properties of ZnSnO thin films by post growth annealing method. Thin films of ZnSnO were grown on Si substrate by evaporating the Zinc and Tin metal powders in the tube furnace. After growth, post growth annealing was performed in open environment using a temperature range of 600−800 °C. The XRD results confirmed the formation of hexagonal closed packed structure of ZnSnO and the crystanality was found to be improved with post growth annealing temperature. The vibrational mode of ZTO at 435 cm−1 was verified by Raman spectroscopy measurements along with other Raman active modes related to single crystal Si and SnO2 as well. Seebeck data demonstrated that the values of Seebeck coefficient were increased from 204 to 1032 μV/°C as the annealing temperature increased from 600 to 800 °C. This increasing behavior of Seebeck coefficient was related with the mobility enhancement of the charge carriers by post growth annealing process. The Hall data supported our argument that mobility of carrier increased with annealing temperature due to high thermal energy. The giant enhancement of Seebeck coefficient and power factor values makes this material a potential candidate for thermoelectric power generation applications in near future.