Multi-crystalline silicon solar cells with metal-assisted nano-texturing using HNO3 as hole injection agent

Abstract

In this study, metal-assisted etching (MAE) with nitric acid (HNO3) as a hole injecting agent has been employed to texture multi-crystalline silicon wafers. It was previously proven that addition of HNO3 enabled control of surface texturing so as to form nano-cone shaped structures rather than nanowires. The process parameters optimized for optically efficient texturing have been applied to multi-crystalline wafers. Fabrication of p-type Al: BSF cells have been carried out on textured samples with thermal SiO2/PECVD-SiNx stack passivation and screen printed metallization. Firing process has been optimized in order to obtain the best contact formation. Finally, j(sc) enhancement of 0.9 mA/cm(2) and 0.6% absolute increase in the efficiency have been achieved. This proves that the optimized MAE texture process can be successfully used in multi-crystalline wafer texturing with standard passivation methods. J-V curves and SEM images of the nano and iso-textured samples. j(sc) enhancement of 0.9 mA/cm(2) together with 0.6% absolute efficiency gain was observed on nano-textured samples