Band alignment and carrier injection at the porous-silicon–crystalline-silicon interface

The current-voltage characteristics and the photoresponse of metal-porous Si–p-type Si heterostructures have been studied. It is shown that the common interpretation of the current-voltage characteristics, which assumes that the current is limited by the Schottky barrier at the metal-porous Si interface, is wrong. An alternative explanation based on the electric-field dependence of the porous Si conductivity is suggested. It is shown that the rectifying behavior originates from a depletion inside the c-Si substrate at its interface to the porous Si.