Thermoelectric Properties of Al Doped ZnO Thin Films Fabricated through Inkjet Printing

Abstract

The effects of Al doping to the thermoelectric properties of ZnO thin films fabricated through ink-jet printing were studied in this paper. Ink-jet printing was used to deposit the Al doped ZnO thin films. A minimum of 50 print cycles was required to obtain continuous film with approximately 9 μm thick thin films. It was possible to obtain high thermoelectric properties of ZnO by controlling the ratios of dopant added and the temperature of the heat treatments.The XRD traces of Al doped ZnO exhibit a polycrystalline hexagonal structure for the wurtzite phase of ZnO. There were no additional phase detected for Al doped ZnO thin films with increasing amount of Al dopants and heat treatment temperature. The results show Al doping had improved the thermoelectric properties of ZnO with an increased in electrical conductivity. The electrical conductivity of pure ZnO thin film (5 S/cm) was enhanced with increasing the dopant to 4wt% Al doped ZnO (114 S/cm). Negative Seebeck values were observed for all the samples that indicated n-type semiconductor. Pure ZnO samples have a measured Seebeck coefficient-17.63 μV/K decreased to-14.35 μV/K with 4 wt% Al doped.