Al掺杂ZnO多晶的热电输运性质研究

Study on the Thermoelectric Transport Properties of Al-doped ZnO Polycrystals

采用固相反应法制备了六方纤锌矿结构Zn_(1-x)Al_xO(0≤x≤0.03)系列多晶,探究了Al掺杂对ZnO多晶的微观形貌和热电输运性质的影响。结果表明,Al掺杂促使ZnO晶粒长大联结,晶界减少,x>0.003时出现在晶界分布的ZnAl_2O_4尖晶石相。掺杂后样品由ZnO的半导体行为转变为电阻率显著下降的金属行为,且x=0.003有最小的室温电阻率~1.7 mΩ·cm,主要由于掺杂使样品载流子浓度和迁移率显著提高,x=0.003时载流子浓度和迁移率为最高,分别为1.05×10^(21)cm^(-3)和20 cm^2/V·s;300~900 K下掺杂样品热电势的绝对值和功率因子均随温度升高而增大,x=0.003时有最大的室温功率因子~0.4 m W/m·K^2。综合得到ZnO中Al掺杂的饱和固溶度x≈0.003。

Zn_（1-x）Al_xO（0 ≤ x ≤ 0. 005） polycrystalline bulks with hexagonal wurtzite structure were prepared by solid-state reaction method. The microstructure and thermoelectric properties of Zn_（1-x）Al_xO bulk were investigated. Doping Al makes ZnO grain increases and grain boundry decreases. The results show that the spinel ZnAl_2O_4 appeared while x 0. 003. The semiconductor behavior of bulks transform metallic behavior after Al doping in ZnO. Al doping is responsible for 1 orders of magnitude decrease of resistivety and the carrier concentration and mobility remarkable increase. At x = 0. 003 the minimum of resistivety is 1. 7 mΩ · cm and the carrier concentration and mobility are maximum. The carrier concentration is 1. 05 × 10^21cm^-3. The mobility is 20 cm^2/V · s at room temperature. The seebeck coefficient and power factor S^2/ρ increases as the temperature increasing at 300-900 K. The maximum of the power factor is 0. 4 m W/m·K^2 at room temperature. The saturated solution of Al doping in ZnO is0. 003.