溅射沉积掺Ag的SnSe薄膜的微结构和热电性能

使用粉末烧结SnSe合金靶高真空磁控溅射制备掺杂Ag的SnSe热电薄膜，利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)等手段分析薄膜的相组成、表面形貌、截面形貌、微区元素含量和元素分布，利用塞贝克系数/电阻分析系统LSR-3测量沉积薄膜的电阻率和Seebeck系数，研究了不同Ag含量SnSe薄膜的热电性能。结果表明，采用溅射技术可制备出正交晶系Pnma结构的SnSe相薄膜，掺杂的Ag在薄膜中生成了纳米Ag₃Sn。与未掺杂Ag相比，掺杂Ag的SnSe薄膜其电阻率和Seebeck系数(绝对值，下同)明显减小。并且在一定掺杂范围内，掺杂Ag越多的薄膜电阻率和Seebeck系数越小。未掺杂Ag的SnSe薄膜样品，其Seebeck系数较大但是电阻率也大，因此功率因子较小。Ag掺杂量(原子分数)为7.97%的样品，因其Seebeck系数绝对值较大而电阻率适当，280℃时的功率因子最大(约为0.93 mW·m^-1·K^-2)，比未掺杂Ag的样品(PF=0.61 mW·m^-1·K^-2)高52%。掺杂适量的Ag能提高溅射沉积的SnSe薄膜的热电性能(功率因子)。

Structure and Thermoelectric Properties of Ag-doped SnSe Thin Films Deposited by Magnetron Sputtering

Ag-doped SnSe thermoelectric thin films were deposited by high vacuum magnetron sputtering using a powder sintered SnSe alloy target. The influence of Ag-doping on the surface and cross sectional morphology, phase composition and thermoelectric properties of the SnSe thin films were investigated by means of X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), as well as Seebeck coefficient/resistance analysis system LSR-3. The results show that the SnSe films are composed of SnSe phase of orthorhombic Pnma structure. The nano-sized Ag₃Sn phase exists in the films with Ag-doping. Compared with the film without Ag-doping, the resistivity and absolute value of Seebeck coefficient of the SnSe films with Ag-doping decrease significantly. In a certain doping range, the more Ag-doping is, the smaller the resistivity and the absolute value of the Seebeck coefficient are. Although the absolute value of the Seebeck coefficient of undoped films is high and the resistivity is relatively large, so the power factor is small. For the film with 7.97% Ag (in atomic fraction), the power factor reaches the maximum at 280℃ due to higher Seebeck coefficient absolute value and appropriate resistivity, accordingly, the maximum power factor is about 0.93 mW·m^-1·K^-2 at 280℃, which is 40% higher than that of undoped films (PF=0.61 mW·m^-1·K^-2). In conclusion, the appropriate amount of Ag-doping can effectively improve the thermoelectric properties (power factor) of the SnSe thin films by magnetron sputtering.