Damage studies in dry etched textured silicon surfaces

Abstract

Surface texturing is a more permanent and effective solution to eliminate reflections compared with antireflection coatings in optical devices. In this study texturing was performed using a reactive ion etching technique, reflectance was measured and the resultant damage on the surfaces was monitored through the minority carrier lifetime measurements. High minority carrier lifetime is an indication of low defect centres and is essential for maximum collection efficiency. It is found that the reflectance of the textured cone structures is less than 0.4% at wavelengths from 500 to 1000 nm and shows a minimum of 0.29% at 1000 nm. while the reflectivity from black silicon is around 1% and from hole structures is around 6.8% in the same wavelength range. The quasi-steady-state photo conductance technique was used to measure the effective carrier lifetimes of the textured samples, showing that chemical wet etch damage removal is effective in improving the lifetime of the sample.