Silicon plasma processing for antireflective micro — Textured surfaces with applications for solar cells

In this paper we present the fabrication of antireflective micro-textured silicon surfaces using ICP (Plasmalab System 100 from Oxford Instruments) dry etching processes for silicon pillars (cylinders, clepsydra, needles). Different etching profiles, sizes and shapes have been obtained through the variation of plasma parameters: pressure, gas debit, etching chemical species. The silicon pillars lower the losses by surface reflection of incident radiation and increase the optical active region of the solar cell, hence increasing device´s conversion efficiency. The influence of pillars with various profiles, forms, sizes and heights has been investigated by recording the reflectance spectra on the silicon textured wafers in the spectral range of 200 ÷ 900 nm using UV_VIS_NIR spectrophotometer. The spectra analysis has shown that the reflectivity of the textured silicon surface using pillars has decreased to 10%-15% compared with the value of 35% for the silicon untextured surface, in the spectral range 400 nm _ 1000 nm. To control and verify the etching rate and the shape of the structures, we used SEM imaging and characterization.