A study of interface properties in a-Si solar cells with mu c-Si(C)

A series of experimental trials have been carried out on the interface properties of a-Si solar cells by utilization of heavily doped microcrystalline silicon (mu c-Si) and its carbon alloys (mu c-SiC) in the front electrode TCO and wide gap window layer p type a-SiC interface. As the result, a remarkable improvement of the photovoltaic performance of not only V-oc but also FF has been obtained due to the reduction of the surface barrier potential at the TCO/p a-SiC interface. An insertion of a thin n-type mu c-Si layer in the TCO/p mu c-Si(C) interface is also useful to improve the FF due to improving the tunnel effect. Special effort has also been made on the p/i interface. A series of differently structured buffer layers of a-SiC are formed at the p a-SiC/i a-Si interface for the improvement of the voltage characteristic. As a result, V-oc has been raised parallel with the built-in potential. The mechanism of the improvements is discussed on the basis of the systematic diagnostics on the interface properties.