Fully low temperature interdigitated back-contacted c-Si(n) solar cells based on laser-doping from dielectric stacks

Abstract

This work shows a novel fabrication process of interdigitated back-contacted c-Si(n) solar cells based on laser-doped point contacts. In this approach, all the highly-doped regions have been entirely fabricated through UV laser processing of dielectric layers, avoiding the high temperature steps typically involved in conventional diffusion processes. Additionally, the number of patterning steps has been significantly reduced. Aluminum oxide films deposited by thermal ALD on the front surface passivate and reduce reflection losses, while at the rear surface the same films are also used as aluminum source for p+ emitter contacts. n+ regions are created by laser processing a phosphorus-doped amorphous silicon carbide stack deposited by PECVD. As a proof of concept, solar cells (3×3 cm2) have been fabricated with efficiencies beyond 20% with short-circuit current densities and open-circuit voltages up to 40.7 mA/cm2 and 654 mV respectively.