Demonstration of c-Si solar cells with gallium oxide surface passivation and laser-doped gallium p+ regions

Abstract

Gallium oxide (Ga2O3) deposited by plasma enhanced atomic layer deposition (PEALD) is shown to passivate crystalline silicon surfaces via a combination of a high negative charge and a reduction in the density of surface defects to below 1×1011 cm-2 eV-1 at midgap. The passivation, as determined by the injection dependent excess carrier lifetime, is demonstrated to be commensurate to that of PEALD aluminium oxide (Al2O3). In addition, Ga2O3 is used as a gallium source in a laser doping process, resulting in an efficiency of 19.2% and an open circuit voltage of 658 mV in a partial rear contact p-type cell design. As such, we demonstrate that Ga2O3 is comparable to Al2O3 in terms of performance and utility, with potential material advantages over Al2O3.