Determination of Internal Electrical Field Profile in a-Si:H Solar Cells

Basic methods for the determination of internal electrical field in a-Si:H solar cells, derived from the standard Time of Flight (TOF) technique, are presented. One of these methods, based on charge collection, is very attractive; is is particularly simple, does not need high time resolution and is insensitive to the transport dispersion. It allows characterisation of the internal electrical over the whole thickness of the i-layer when bifacial p-i-n a-Si:H solar cells are used. Use and limits of this specific method are presented and discussed. Furthermore, some examples of field engineering in p-i-n are shown.