Multicrystalline Silicon Solar Cell Improvement by Atmospheric Pressure Dry Etching Process

Abstract

In this paper, a plasma-less atmospheric pressure dry texture process that is capable of forming nanostructures in the c-Si surface, has been investigated. The texture process uses diluted molecular fluorine (F2) as the process gas. Thermal activation of fluorine occurs on Si wafer surface in a dissociative chemisorption process leading to removal of Si in the form of volatile SiFx species. The etching process can be controlled to form nanostructures with different aspect ratios and surface reflection values. Nanotexturing of mc wafers was performed by removing very low amount of Si substrate during the texturing process (~0.6 μm). These nanotextured wafers were further processed into p-type Al-BSF solar cells. The nanostructured cells show excellent Voc and FF that are comparable to the reference cells. Significant gain in short circuit current (Jsc) was achieved by the virtue of an enhanced light coupling in nanotextured solar cells. The best conversion efficiency of 17.3% was achieved for the mc Al-BSF cell. Adaptation of the emitter on nanotextured surface has potential to further increase the conversion efficiency.