退火温度对Bi_2Te_(2.7)Se_(0.3)薄膜的微结构及热电性能的影响

Effects of Annealing on Microstructure and Thermoelectric Properties of Bi_2Te_(2.7)Se_(0.3) Thin Films

采用瞬间蒸发技术在温度为473 K的玻璃基体上沉积了厚度为800 nm的N型Bi2Te2.7Se0.3热电薄膜,并在373 K～573 K进行1小时的真空退火处理。利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和能量散射谱(EDS)分别对薄膜的物相结构、表面形貌以及化学计量比进行表征。采用表面粗糙度测量仪测定薄膜厚度,薄膜的电阻率采用四探针法在室温下进行测量,在室温下对薄膜的Seebeck系数进行表征。霍尔系数,电子浓度和迁移率在300 K用Van der Pauw方法进行测量。退火温度为473 K时,电阻率和Seebeck系数分别为2.7 mΩ.cm和?180μV/K,热电功率因子最大值为12μW/cmK2。

N-type Bi2Te2.7Se0.3 thermoelectric thin films with thickness 800 nm were deposited on glass substrates by flash evaporation method at 473 K.Effects of annealing on the thermoelectric properties of Bi2Te2.7Se0.3 thin films were examined for the samples annealed at 373 K–573 K for one hour.The structures,morphology and chemical composition of the thin films were characterized by X-ray diffractometry,field emission scanning electron microscopy and energy dispersive X-ray spectroscopy,respectively.Thermoelectric properties of the thin films have been evaluated by measuring electrical resistivity and Seebeck coefficient at 300 K.The Hall coefficients were measured at room temperature by the Van der Pauw method.The carrier concentration and mobility were calculated from the Hall coefficient.When annealed at 473 K,the electrical resistivity and Seebeck coefficient are 2.7 mΩ·cm and -180 μV/K,respectively.The maximum thermoelectric power factor is enhanced to 12 μW/cmK2.