Investigation of the surface passivation quality of various novel low temperature rear localized contacting schemes for photovoltaic devices

A novel localized rear contacting scheme suitable for commercial photovoltaic devices has been developed and demonstrated without requiring any physical or photolithography based techniques. This simple and low cost technique utilizes aluminum spiking to randomly reduce localized regions of a surface passivating silicon dioxide layer at elevated temperature (but below the eutectic temperature of Al and Si, i.e., 577 °C) to form conductive paths to the underlying substrate. The Al can be further utilized to induce solid phase epitaxial growth of p⁺ silicon in these localized regions via subsequent amorphous silicon deposition and low temperature sinter. This work uses the photoconductance decay lifetime measurements to investigate and compare the rear surface passivation and bulk minority carrier lifetime of devices after applying various localized contacting techniques including photolithography based approaches.