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

Gallium oxide (Ga ₂ O ₃ ) 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 1×10 ¹¹ 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 (Al ₂ O ₃ ). In addition, Ga ₂ O ₃ 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 Ga ₂ O ₃ is comparable to Al ₂ O ₃ in terms of performance and utility, with potential material advantages over Al ₂ O ₃ .