退火温度对CuGa_(0.8)Ge_(0.2)Se_2薄膜结构及光学特性的影响

Influence of Annealing Temperature on Microstructures and Optical Properties of CuGa_(0. 8)Ge_(0. 2)Se_2 Films

采用脉冲激光沉积法在SiO2衬底上制备了CuGa0.8Ge0.2Se2薄膜。采用X射线衍射和X射线能谱仪研究了退火温度对薄膜晶体结构和成分的影响,利用扫描电子显微镜表征了薄膜的表面形貌,采用紫外—可见分光光度计分析了薄膜的光学特性。结果表明,在CuGaSe2中掺杂Ⅳ族元素Ge,光子吸收能量分别为0.65和0.92 e V,禁带宽度为1.57 e V,能够形成中间带。并随着退火温度的升高,CuGa0.8Ge0.2Se2薄膜的光学带隙逐渐减小。

The CuGao.sGeo.2Se2 thin films were synthesized by pulsed laser deposition （PLD） on SiO2 substrates. The influence of the growth conditions, including but not limited to the annealing temperature, laser intensity and Ge-con- tent,on the optical properties of the coating was investigated. The CuGao.sGe0.2Se2 thin films were characterized with X- my diffraction, energy dispersive spectroscopy, scanning electron microscopy and ultraviolet visible spectrophotometer. The results show that the Ge-doping and annealing temperature strong affect the microstructures and optical properties. For in- stance,as the annealing temperature increased, the averaged size of CuGa0.sGe0.2Se2 grain increased, accompanied by a decrease of the optical band-gap; and the 〈 112 〉 preferential growth orientation was most pronounced at 600℃. The Ge- doping resulted in formation of an intermediate band. The distinctive photon absorption energies were found to be 0.65 and 0.92 eV. The gap was calculated to be 1.57 eV.