Nanostructuring of c-Si surface by F₂-based atmospheric pressure dry texturing process

Abstract

A novel atmospheric pressure dry texture process is investigated in order to create nanostructures at the c-Si surface. The texture process uses diluted molecular fluorine (F2) as the process gas. F2 is partially dissociated at an elevated temperature before it is delivered to the c-Si wafer. Thermal activation of fluorine occurs on Si wafer surface in a dissociative chemisorption process leading to the 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. In this work, we dry textured multicrystalline (mc) Si wafers to reach weighted surface reflection ∼12% in the wavelength range of 250–1200 nm. Nanotextured mc Si wafers were used to prepare p-type Al-BSF solar cells. The fabricated nanostructured cells show a gain in short circuit current (Jsc) of ∼0.5 mA/cm2 and reached a conversion efficiency of 17.3%.