The Application of a-Si:H/AlOx Stack as An Electron Selective Contact on N-type Silicon Solar Cells

In this report, we present a novel application of ALD (atomic layer deposition) deposited aluminum oxide (AlO x ) combined with a passivation layer of a-Si:H(i) (hydrogenated intrinsic amorphous silicon) as electron selective contacts (ESCs) on n-type silicon (n-Si) solar cells. Band alignment profiles of n-Si/Al, n-Si/AlO x /Al and n-Si/a-Si:H(i)/AlO x /Al structures are presented, suggesting the feasibility of electron-selectivity, and explaining the transformation from a Schottky behaving contact to an ohmic contact. As proof, a rectifying Al contact on n-Si is observed to be ohmic after the inclusion of an AlO x interlayer. A contact resistivity as low as 3.45 ± 0.005 mΩ•cm ² is obtained. Finally, a cell achieving an open-circuit voltage of around 590 mV has been fabricated to demonstrate the feasibility of this contact technique.