Experiments on polystyrene films formed by a glow-discharge technique shows a reproducible bistable switching. Various interpretations are briefly reviewed. It is shown that the resistance of the on state is strictly related to the energy needed by the on-off transition. From the value of this energy it is concluded that the most probable explanation is that the on current takes place along a filamentary path constituted by carbon atoms. A quantitative analysis is made on the basis of the heat balance equation. Formation of carbonated chains is confirmed by a chromatography analysis in vapor phase which shows an hydrogen release.

Reproducible bistable switching has been observed in Au-Polymer-Au junctions. The polymer is formed by a glow-discharge polymerization technique. The resistance ratio is more than 107 and structures can be switched more than 2000 times. When the polymer thickness is lower than 1500 Å, the threshold voltage increases linearly with the polymer thickness. A scanning electron microscope picture of a junction that has been switched shows circular dots, ranging between 5- and 10- μm diameter, on the surface. These dots are probably due to current-carrying filaments.

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