Effects of hydrogen absorption on the electrical conduction of discontinuous palladium thin films

The continuation of work reported earlier (Morris and Wu 1994) on the development of a discontinuous thin palladium film hydrogen sensor confirms the effects first described and interpreted by Barr (1977). The basic principle is that quantum-mechanical tunnelling between the discrete metal islands of the film is modulated by barrier height increases due to the surface adsorption of hydrogen, and by gap reduction due to island lattice swelling. Transient thermal effects do not yet permit quantitative verification of the model.