The use of chemical vapor etching in multicrystalline silicon solar cells

Centre de Recherches et des Technologies de l'Énergie – Technopole de Borj-Cédria, Laboratoire de Nanomatériaux et des Systèmes pour l'Énergie, BP 95, 2050 Hammam-Lif, Tunisia

Corresponding author: rabha2222@yahoo.fr

Received: 13 June 2008
Revised: 20 October 2008
Accepted: 7 March 2009
Published online: 7 May 2009

Abstract

With the purpose to increase the light confinement and the efficiency of silicon solar cells, the reflection of the surface emitter needs to be minimized and the minority carrier collection improved. This improvement is currently achieved by the application of the chemical vapor etching (CVE) technique. In this paper, we investigate the effects of CVE on surface texturing and silicon grooving. CVE-based porous silicon (PS) was found to be a good antireflection and passivation layer for multicrystalline Si (mc-Si) solar cells. As a result, the reflectivity of the mc-Si solar cell decreases by about 60% of its initial value in the 650–950 nm spectral range and the internal quantum efficiency improves by 30% after PS application in the 400–700 nm spectral range. CVE can be used for surface texturing of single or mc-Si Si wafer leading to lower surface reflectivity and reduction of the dead layer. The chemical vapor etching techniques enabled realize buried metallic contacts by grooving mc-Si silicon wafers. The spectral response of mc-Si solar cells was found to enhance of about 12% in the long wavelength range when a rear buried metallic contacts is achieved, while a significant increase of about 35% was observed at short wavelengths (400–650 nm spectral range) subsequent front grid buried metallic contacts realization.