High-Efficiency c-Si Solar Cells Passivated With ALD and PECVD Aluminum Oxide

Ultrathin (7 nm) atomic layer deposited Al
₂
O
₃
layers and high-deposition-rate plasma-enhanced chemical vapor deposited AlO
_x
layers have been applied and characterized as rear-surface passivation for high-efficiency silicon solar cells. The excellent efficiency values (up to 21.3%-21.5%) demonstrate that both aluminum oxide deposition processes have a very high potential comparable to the reference cells with SiO
₂
passivation. The high voltages ( 680 mV), the excellent long-wavelength quantum efficiency, and the high short-circuit currents of these cells (~40 mA/ cm
²
) are a proof for the low rear-surface recombination velocity and excellent internal rear-surface reflection.