Thermoelectric properties optimization of Al-doped ZnO thin films prepared by reactive sputtering Zn–Al alloy target

Abstract

Al-doped ZnO (AZO) has practical applications in the industry for thermoelectric generation, owing to its nontoxicity, low-cost and stability at high temperatures. In this study, AZO thin films with high quality were deposited on BK7 glass substrates at room-temperature by direct current reactive magnetron sputtering using Zn–Al alloy target. The deposited thin films were annealed at various temperatures ranging from 623K to 823K with a space of 50K. It is found that the absolute value of Seebeck coefficient of AZO thin film annealed at 723K increases stably with increasing of measuring temperature and reaches a value of ∼60μV/K at 575K. After that, Al-doping content was varied to further optimize the thermoelectric properties of AZO thin films. The power factor of AZO thin films with Al content of 3wt% increased with increase of measuring temperature and the maximum power factor of 1.54×10−4Wm−1K−2 was obtained at 550K with the maximum absolute values of Seebeck coefficient of 99μV/K, which is promising for high temperature thermoelectric application.