Method for producing photovoltaic device isolated by porous silicon

Abstract

Photovoltaic devices are produced using a minimally modified standard process flow by forming lateral P-I-N light-sensitive diodes on silicon islands that are isolated laterally by trenches performed by RIE, and from an underlying support substrate by porous silicon regions. P+ and N+ doped regions are formed in a P− epitaxial layer, trenches are etched through the epitaxial layer into a P+ substrate, a protective layer (e.g., SiN) is formed on the trench walls, and then porous silicon is formed (e.g., using HF solution) in the trenches that grows laterally through the P+ substrate and merges under the island. The method is either utilized to form low-cost embedded photovoltaic arrays on CMOS IC devices, or the devices are separated from the P+ substrate by etching through the porous silicon to produce low-cost, high voltage solar arrays for solar energy sources, e.g., solar concentrators.