晶体硅金字塔绒面结构圆化对其光反射率和非晶硅薄膜钝化效果的影响

Effects of Rounding of Pyramid Texture on Light Reflectivity and Amorphous Silicon Thin Film Passivation of Crystalline Silicon

(001)晶体硅金字塔绒面结构圆化有提高光反射率与提高非晶硅薄膜钝化效果的相互矛盾的双重作用,定量了解它们对优化非晶硅/晶体硅异质结太阳电池的绒面结构圆化程度很有必要。本文以表面粗糙度Rz相对下降百分数定量表征晶体硅衬底表面金字塔绒面结构圆化程度DR,研究了DR值对等离子体化学气相沉积氢化本征非晶硅薄膜钝化效果的改善作用,发现除圆化初期效果异常高以外,二者之间基本呈线性正比关系;相对改善作用随钝化膜变薄而显著提高。同时测定了DR值对金字塔绒面光反射率的影响,发现反射率基本随DR值线性增大。典型结果为:6%绒面结构圆化程度下,金字塔绒面的光反射率绝对值提高3%;其表面7 nm厚的氢化本征非晶硅薄膜可达到使硅片少数载流子寿命相对未圆化绒面样品提高260%。

Rounding of pyramid texture on（ 001） crystalline silicon has contradicting dual effects on its light reflectivity and its passivation function by thin film hydrogenated amorphous silicon, making quantitative understanding of the effects important to optimization of the degree of the rounding for processing of amorphous silicon / crystalline silicon heterojunction solar cells. Relative decrease of roughness Rzis used to quantitatively characterize the degree of rounding,DR. Improvement of the passivation by PECVD thin films of hydrogenated amorphous silicon from the rounding of the texture was experimentally studied. The results indicate that a basically linear increase of the minor carrier lifetimes with increase of DR value,except the initial extraordinary phenomenon.The relative improvement with thinner films is found to be more sensitive to the DR value. Dependence of light reflectivity on the DR value is measured,and a linear relationship is identified. A typical result is： 260% relative increase of minor carrier lifetime can be achieved by a rounding with DR of 6%,when the passivation film is 7 nm thick. A 3% absolute increment in light reflectivity of the naked rounded surface is also generated.