Porous silicon‐based microtexturing of textured monocrystalline silicon solar cells

Abstract

This work aims to examine the effects of surface micro‐texturing on the performances of pyramidal textured monocrystalline silicon (c‐Si) photovoltaic solar cells. The surface micro‐textures were performed on the emitter of alkaline‐textured PV solar cells without damaging the junction, using the HNO3/HF vapor etching (VE) method. Scanning Electron Microscopy (SEM) shows that vapour etched pyramidal textures exhibit a high texture density essentially composed of porous silicon (PS) microstructure. The VE technique notably decreases the surface reflectivity from 12% for alkaline‐textured c‐Si wafers to about 6% after micro‐texturing. Subsequent to VE, the sheet resistance was found to increase indicating a reduction of the dead layer. Fourier Transform Infrared Spectroscopy (FTIR) measurements showed that the PS‐based micro‐textures are hydrogen‐rich, which could have passivation capabilities of the emitter. Taking into account basic phenomena occurring during carrier photogeneration and minority carrier collection, we tried explaining the variation of the short circuit current density (Jsc), the open circuit voltage (Voc) and the Fill factor (FF) due to PS‐microtexturing of the emitter of c‐Si solar cells (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optimization of silicon pyramidal emitter by self-selective Ag-assisted chemical etching

“…On the other hand, post-chemical treatments, such as HF dipping, 1 alkali treatment 9,10 and HNO 3 /HF vapor etching, 11 are effective and low-cost for removing the dead layer. However, pyramidal emitters are not uniform; they show a deeper junction at the peak and a shallower junction at the valley.…”