Papers by Author: Dong Ping Zhang

Abstract: Significant progress has been made in thermoelectric materials during the last decades and it is found that thermoelectric thin film materials have high thermoelectric conversion efficiency. ZnO based thermoelectric materials, such as ZnO:Al (AZO), are considered as the most promising oxide materials for high-temperature, nontoxic and low-cost thermoelectric application. In this work, the effects of annealing temperature on the thermoelectric properties of AZO thin films prepared by direct current magnetron sputtering were investigated. The results indicate that the Seebeck coefficient of AZO thin films increases and the resistivity decreases as increasing of annealing temperature. Among the prepared AZO films in this work, the maximum absolute value of Seebeck coefficient is 460 μV/K and the minimum resistivity is 3.25×10^-4 Ω·m. The sample annealed at 773 K has a maximum power factor value of 1.46×10^-4 W/mK² at 620 K with a moderate Seebeck coefficient of-355 μV/K and a electrical conductivity of 1.16×10³ S/m.

Abstract: N-type Bi2Te3 and p-type Sb2Te3 thermoelectric thin films have been prepared by RF and DC co-sputtering. The Seebeck coefficient of n-type Bi2Te3 and p-type Sb2Te3 thin films is about -122 μVK-1 and 108 μVK-1, the power factor is about 0.82×10-3 Wm-1K-2 and 1.60×10-3 Wm-1K-2. Then, the films have been selected to fabricate the thin film thermoelectric generator. The results show that the open-circuit voltage of 12.2 mV and the output power of 3.32 μW are obtained for a thin film generator with the temperature difference at 60 K.

Abstract: To evaluate the influence of plasma power on the structural, electrical and optical properties of Al-doped ZnO (AZO) films, a set of polycrystalline AZO samples under different plasma power were deposited on glass substrates at room temperature. X-ray diffraction technique (XRD), four-point probe measurements and spectrophotometer were used to characterize these films. XRD shows that all AZO films have a hexagonal wurtzite structure with prominent (002) orientation. With the plasma power increasing, the grain size first increases and then decreases. The largest grain size of 23.6 nm in the films is obtained at the plasma power of 123 W. The average optical transmittance of AZO films is over 80% in the visible region. The lowest resistivity of 1.0×10^-3Ω•cm is obtained under the plasma power of 220 W.