载气对CIGS薄膜结构和表面形貌的影响

Influence of Carrier Gas on Microstructures and Morphologies of Cu(In_(1-x)Ga_x)Se_2 Films

采用中频交流磁控溅射方法,在Mo层上沉积了CuInGa(CIG)预制膜。分别以N2和Ar为载气,采用硒蒸汽硒化法制备了Cu(In1-xGax)Se2(CIGS)吸收层薄膜,考察了N2和Ar流量对CIGS薄膜结构和形貌的影响。采用SEM和EDS观察和分析了薄膜的表面形貌和成分,采用XRD表征了薄膜的组织结构。结果表明,采用Ar和N2为载气时,在各个流量下所制备的CIGS薄膜均为黄铜矿相结构,薄膜具有(112)面的择优取向。采用Ar为载气时,当Ar流量为0.10 m3/h时,所获得的CIGS薄膜的孔隙最少,随着Ar流量的增大,薄膜孔隙增多,变得疏松。采用N2为载气时,当N2流量为0.10 m3/h、0.20 m3/h、0.30 m3/h时,所获得的CIGS薄膜孔隙较多,当N2增大到0.40 m3/h时,薄膜变得致密,所获得的CIGS的CuI、n、Ga原子含量,处于制备弱p型CIGS薄膜的理想范围。

Cu（In1-xGax）Se2 films （CIGS） absorbers were grown by selenizing the CuInGa（CIG） precursors, deposited by mid frequency AC sputtering of CuIn and CuGa targets, sequentially, on Mo-coated glass substrates in an atmosphere of Se vapor and the carrier gas of either N2 or Ar. The CIGS films were characterized with X-my diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）. The results show that the type and flow rate of the carier gas considerably affect the microstrcutures and morphologies of the CIGS films. For example, at various carrier gas flow rates, the CIGS films show a chalcopyrite phase with （112） as the preferred growth orientation. The most compact surfaces,with minimum surface pore density,can be obtained at an argon flow rate of 0.10 m^3/h.As the Ar flow rate increases, the film becomes less compact with increased surface pore densities. In contrast, as the nitrogen flow rate increases from 0.10 m^3/h, the film looks rather rough with high surface pore densities;however, at a rate of 0.40 m^3/h, the films become fairly compact.We suggest that the optimized N2 flow rate is 0.40 m^3/h in growing the weakly p-typed CIGS films with good stoichiometires of Cu, In, and Ga.