Surface Flashover of Silicon

We have previously reported the results of experiments based on high-speed shutter and streak photography which show clearly that in surface flashover of silicon in a vacuum ambient the current flows primarily in the silicon, not in the ambient. Here we present scanning electron microscope (SEM) photographs of the surface damage resulting from flashover which show that this current is filamentary. Photomicrographs obtained from samples with diffused p/sup +/ and n/sup +/ contacts show that the contacts exert a strong influence over the flashover characteristics. Finally, we report the results of experiments in which the sample was illuminated with a weak pulse of visible light either before or just after the application of the voltage pulse to the sample. These experiments show that flashover can be inhibited by such a light pulse, and shed light on the relationship between the flashover mechanism and electric field inhomogeneities.