Table of Contents
International Journal of Plasma Science and Engineering
Volume 2008, Article ID 371812, 5 pages
http://dx.doi.org/10.1155/2008/371812
Research Article

Microstructures Formation by Fluorocarbon Barrel Plasma Etching

1Silicon Technology Unit. 2, Boulevard Frantz Fanon, BP 140 Alger-7 merveilles, Algiers 16200, Algeria
2Advanced Technologies Development Centre, cité 20 Aout 1956, BP 17, Baba Hassen, Algiers, Algeria

Received 27 March 2007; Revised 7 August 2007; Accepted 17 September 2007

Academic Editor: Rami A. Kishek

Copyright © 2008 A. El amrani et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The aim of our study is to generate microstructures in order to improve optical properties of monocrystalline silicon. By mean of fluorocarbon plasma barrel texturing and under certain process conditions, silicon turned black. As a result of silicon surface-plasma particles reactions, porous microstructures are formed, while a longer process time microspikes are developed. These microstructures are responsible of the high level of light trapping on almost the whole range of the usable portion of the solar spectrum. In the wavelength range of 400–1100 nm, the AM1.5G weighted reflection has been reduced to 6.20%. In addition to good trapping, this surface morphology leads to superior absorption, which is about 95% in the 600–1000 nm range and decreases to 36% at 1200 nm. This material is thus less transparent and absorbs near infrared light far more than the untreated silicon. Secondary ion mass spectrometry shows that elements from the ambient gas are deposited or superficially introduced into the silicon. In addition to surface texturing, these impurities are probably the reason of absorptance enhancement. Moreover, a pore formation mechanism is proposed.