n-type conduction in noncrystalline chalcogenides.

Most amorphous chalcogenides show p-type conduction. Their electrical properties are slightly affected by doping, which has been explained as the result of a strong pinning of the Fermi energy, E//F, near midgap by positively and negatively charged dangling bonds. In the literature a number of attempts have been described to increase the conductivity and to modify the conduction type by doping with various foreign atoms. In a first part of this contribution a brief review of the preparation and properties of chemically modified chalcogenide systems showing a p yields n transition will be presented. Depending on the way of preparation two classes of materials are considered: thin films deposited from the vapor phase and glasses quenched from the melt.