低反射率多晶硅绒面的湿法制备研究

Study on Preparation of Low Reflectivity Multicrystalline Silicon by Wet Etching

在多晶硅太阳电池制备工艺中,多晶硅表面制绒一直是研究热点,绒面的反射率以及形貌受到多个因素的影响。采用由HF,HNO3和H2O组成的腐蚀液对多晶硅进行腐蚀,研究了腐蚀时间,腐蚀液中HF与HNO3的体积比以及H2O在腐蚀液中的含量对制绒结果的影响。用分光光度计测量了制备绒面的反射率,并用扫描电镜观察了制备绒面的表面形貌。研究结果表明,腐蚀液中HF,HNO3和H2O的体积比对腐蚀坑的形貌有重要影响,而腐蚀坑形貌则决定了绒面反射率的高低。当腐蚀液中HF∶HNO3∶H2O体积比为5∶1∶2且腐蚀时间为3 min时,绒面在300 nm～900 nm波长范围内平均反射率最低,仅为20.4%,这是因为绒面中窄而深的腐蚀坑增强了硅片表面对光的吸收,降低了反射率。

In the preparation process of muhicrystalline silicon solar cells, muhicrystalline silicon surface texturing is a hot research topic at all times. The surface reflectivity and morphology of the textured silicon are affected by various factors. The muhicrystalline silicon wafers were etched in the mixed solution of HF, HNO3 and H2O. Etching time,the volume ratios of HF and HNO3 and the volume of H2O in the solution were studied. The surface reflectances of the etched muhicrystalline silicon wafers were analyzed by spectrophotometer and the morphologies of the Ltextured silicon wafers were observed by scanning electron microscopy. It was found that the volume ratios of HF, HNO3 and HE O has a major impact on the morphologies of etching pits, which determine the surface reflectivity. The surface reflectivity in the range of 300 nm and 900 nm is only 20.4% when the solution volume ratio of HF,HNO3 and H20 is 5：1：2 and the etching time is 3 min, which is resulted from the narrow and deep etching pits in the textured silicon surface, where the absorption of light is increased and the reflectivity is reduced.