Etch-back simplifies interdigitated back contact solar cells

Abstract

The process of making Interdigitated Back Contact (IBC) solar cell is implemented by a novel simplified etch-back technique, while aiming for no compromise on high-efficiency potentials. Simplified etch-back creates localized heavy and light phosphorus and boron diffusions simultaneously. This process also leaves localised heavy diffusions to be approximately a micron higher than neighbouring light diffusion regions. In comparison to the IBC solar cells that ANU developed to date [1], key advantages of this technique feature reduction in cell process steps; requires only two diffusions to create p, p+, n and n+ diffusions; no high-temperature oxidation masking steps required as diffusion barriers; independent optimization of contact recombination, lateral carriers transport and surface passivation; and potential higher silicon bulk lifetime and reduced contamination due to low thermal budget. Based on the etch-back technique, the total saturation current density deduced from the test structures for the IBC cell is below 30 fA/cm2.