Abstract: A method of doping amorphous semiconductor films have a first bandgap by forming the first bandgap amorphous material in a first plurality of spaced apart layers; and then forming a second plurality of semiconductor layers of amorphous material having a second bandgap wider than the first bandgap interleaved with and contiguous with the first plurality such that the conductor and valence band step at the interfaces between the first plurality and the second plurality is of sufficient magnitude to confine carriers. The second plurality is doped such that the electrons in the gap states from the second plurality of layers transfer to the first plurality of layers and cause the conductivity of said first plurality to increase.