Novel silicon solar cell fabrication process

Abstract

A frame for fabrication of novel Si solar cells at the micro and nanotechnology laboratory (MiNaLab) at the University of Oslo (UiO) has been established. The focus has been on reproducibility and the possibility to modulate the steps in the process. The process incorporates random pyramidization by KOH-etch for increased light absorption, thermally grown dry-oxide for passivation and anti reflective coating and fabrication of both thin and standard emitters. For emitter formation both ion implantation and spin on diffusant (SOD) were tested. Rapid thermal activation was utilized for low diffusion and high activation fraction. Back side contacts were formed by evaporation of aluminium. Front side contacts were photo lithography defined, featuring titanium, palladium and silver stack. A total of nine different front side metalization patterns were made, optimized for three different sheet resistances and three finger widths. The cells have been electrically, structurally and optically characterized.