A new method was implemented for the fabrication of solar cells on single crystalline Si wafers. The new method employs a thin porous Si layer as an anti-reflective coating and relies on the enhanced properties of metal/porous-Si Schottky contacts. Porous Si is comprised of a 20% to 80% interconnected pores in otherwise single-crystalline Si skeleton. Light incident on the porous structure penetrates the porous layer, undergoes multiple internal reflections and then is absorbed. This process minimizes reflection and enhances absorption. High absorption rate, in turn, results in a higher rate of carrier generation and thus higher cell efficiency. Without the porous layer, a large fraction of the incident light will be reflected at the specular wafer surface.

Conventional fabrication of solar cells involves the utilization of thin oxide layers which act as an antireflective coating, in order to enhance the absorption cross-section of the incident light. However, the scheme of oxide deposition and surface texturing employed by the current technology requires a rather complicated procedure and is costly compared to the new approach. In addition, Schottky barrier solar cells do not require the formation of p n junctions and thus are easier to fabricate.

In this project, we have fabricated and characterized a Schottky barrier solar cell. All the fabrication processes were carried out at room temperature. The porous layer was made by anodizing the Si wafer in a solution of HF and ethanol while the metal deposition was carried out using electron beam evaporation.