Technological process for a new silicon solar cell structure with honeycomb textured front surface

This paper presents a new silicon solar-cell structure improved by texturisation of the front surface using silicon micromachining technologies. A 'honeycomb'-textured front surface has been obtained through a photolithographical process to generate patterns (disc holes) on the front surface followed by isotropic etching (in HNO3: HF: CH3COOH) until the wells joined together. For front-surface loss characterisation, the spectral dependence of the front-surface reflectivity has been investigated by spectrophotometrical measurements. The surface reflectivity was lowered under 10% and this value was a good one compared to the reflectivity of silicon monocrystalline wafer untextured surface. The p-n junction made by phosphorous diffusion at similar to 0.8 mu m follows the honeycomb profile. In order to obtain low series resistance, a p + boron diffusion on the back of the structure was made. The fabrication process was completed with an ohmic contact (Al on top and on the back surface). (c) 2006 Elsevier B.V. All rights reserved.