TRANSPORT OF HYDROGEN IN FILMS OF GRAPHITE, AMORPHOUS-SILICON, AND NICKEL-OXIDE

A new concentration pulse method is used to study the transport of hyd rogen in three semiconducting materials deposited in the form of films on nickel substrates. The most probable models for the transport are proposed. In graphite hydrogen diffuses in the form of molecules and i ts diffusion is accompanied by reversible capture; transport occurs al ong microscopic voids between scales of graphite. Valence unsaturated bonds at the boundaries of the scales serve as capture centers. Diffus ion in amorphous silicon is also accompanied by capture, but takes pla ce in an atomic form along interstices; valence unsaturated Si-bonds s erve as capture centers. In nickel oxide, as in graphite, diffusive tr ansport takes place in the form of molecules, but capture of hydrogen on valence unsaturated bonds has not been observed. A comparative anal ysis is made of the properties manifested by these materials for oxyge n in order to establish their correlation with the structure and elect ronic properties of the semiconductors. (C) 1997 American Institute of Physics.