Mo薄膜性质及对CIGS形貌和结构的影响

Influence of Microstructures of Back-Contact Mo-Coatings on Properties of Cu(In,Ga)Se_2 Solar Cells

分别用磁控溅射法和共蒸法沉积了Mo和CIGS薄膜。考察了气压和CIGS高温沉积环境对Mo薄膜的影响,研究了Mo基底对CIGS结构和形貌的影响,给出了不同Mo基底上制备的电池效率。结果显示,Mo薄膜具有较强的(110)晶面择优取向,低气压沉积的薄膜结构致密,而高气压沉积的薄膜疏松多孔隙。经CIGS高温工艺后,Mo薄膜晶粒融合,形貌特征消失,其中0.1 Pa沉积的Mo薄膜晶粒融合后表面致密无孔隙,方阻下降,而高气压薄膜孔隙变大,方阻上升。高气压沉积的Mo薄膜中Se扩散现象明显,而低气压薄膜结构致密,有利于遏制Se的扩散。Mo薄膜对CIGS的生长有显著的影响,致密平整的Mo薄膜有利于CIGS晶粒长大形成柱状晶结构,并具有(112)晶面择优取向,而疏松的Mo膜上沉积的CIGS呈等轴晶结构,具有(220/204)晶面择优取向。电池结果显示,0.1 Pa沉积的Mo膜上制备的电池效率达到13.42%,气压增大时,填充因子显著降低,转换效率随之下降。

The Cu（In,Ga）Se2（CIGS） solar-cells were fabricated by co-evaporation on dc magnetron sputtered Mo back-contact. The impact of the microstructures of Mo-layers on CIGS solar cells＇ properties was investigated with X-ray diffraction,X-ray photoelectron spectroscopy and scanning electron microscopy. The results show that the Mo-layer＇s surface morphology strongly affected the CIGS solar cells. For example,as the sputtering pressure increased,the sheet-resistance,surface-roughness and porosity of the（ 110） preferentially oriented Mo-layer increased. The CIGS,with bigger columnar（ 112） preferentially grown grains,was fabricated on the compact Mo-layer deposited at a low pressure,in which show a weak diffusion of Se; whereas the CIGS,with smaller（ 220） and（ 204） preferentially grown equiaxed grains,were made on the porous Mo-layer. The CIGS efficiency,fabricated on the Mo-layer,deposited at 0. 1 Pa,was 13. 42%. A higher porosity of Mo-layer（ sputtered at a higher pressure） resulted in a lower efficiency and fill factor.