Obtaining a higher Voc in HIT cells

We have achieved a very high conversion efficiency of 21.5% in HIT cells with a size of 100.3 cm(2). One of the most striking features of the HIT cell is its high open-circuit voltage V-oc, in excess of 710 m V. This is due to the excellent surface passivation at the a-Si/c-Si heterointerface realized by Sanyo's successful technologies for fabricating high-quality a-Si films and solar cells with low plasma damage processes. We have studied ways to treat the surface to produce a good interface throughout our fabrication processes. We have also investigated the deposition conditions of a-Si layers for optimizing the barrier height for the minority carriers in the heterojunction. Our approach for obtaining HIT cells with a high V-oc is reviewed here. Copyright (c) 2005 John Wiley & Sons, Ltd.