Abstract
Here we present modeling results on crystalline Si (c-Si)/amorphous Si (a-Si) heterojunction solar cells using a physical simulation which includes various models for the defect states in the a-Si barriers, as well as explicit models for the ITO emitter contact. We investigate the impact of the band offsets and barrier heights of the a-Si/c-Si interface, particularly in terms of the open circuit voltage. It is also shown that the solar cell performance is sensitively dependent on the quality of the a-Si in terms of defect states and their distribution, particularly on the emitter side. Finally, we analyze the role of tunneling and thermionic emission across the heterointerface in terms of transport from the Si to the ITO contact layer.