ABSTRACT
This chapter presents the experimental evidence observed for the impurity photovoltaic (PV) effect expected from multilayer device structures. In addition, if the incorporation of phenomena such as impact ionisation and impurity PV can be built into the same device, the performance of a solar cell can be enhanced. The three most important steps for an efficient solar cell are satisfied for this structure according to solidstate physics principles, namely the absorption of a major part of the solar spectrum, the creation of e-h pairs in the presence of an internal electric field. It also includes the effective separation of charge carriers towards two electrical contacts and transport through an external electric circuit. A graded bandgap multi-layer solar cell device structure has been designed to effectively absorb ultraviolet, visible, and infrared radiation and to incorporate impact ionisation and impurity PV effects within one device.
