abstract
Spatial Atomic Layer Deposition (SALD) had been successfully applied in the past for the Al2O3 surface passivation on silicon solar cells. In contrast to conventional sequential ALD techniques, as typically used in the labs, SALD allows for high deposition rates of a few nm per second, which are compatible with industrial solar cell production. In this contribution, we apply SALD for the first time to the electronic passivation of moderately doped (\~1016 cm--3) p-type crystalline silicon surfaces with thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400°C in air, an effective surface recombination velocity Seff of only 4 cm/s is achieved, which is below what has been reported before using sequential ALD techniques. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. Firing is shown to reduce the passivation quality, however, by adding a capping layer of plasmaenhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the HfO2, the firing stability is found to improve. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future silicon solar cells.