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It is described that the shape of the high current density path formed between Au electrodes on the surface of glass semiconductor depends on the composition of sample, and an analysis using one dimensional model is studied. As a result, it is understood that the difference of the filamentary shape from material to material depends on the material constants: ΔE and σ0 where ΔE is the activation energy, σ0 the electrical conductivity; σ=σ0exp (-ΔE/kT),).

The light-induced memory effect in amorphous selenium films is studied by fabricating them into a sort of heterojunction (Se-SnO(2)) so as to be able to apply the bias voltage together with the laser beam irradiation for memory. Under the reverse bias voltage, a region of high electric field is formed in the selenium film near the junction. Remarkable enhancement in the photo-induced image spot is achieved if an appropriate bias voltage is applied simultaneously, indicating the sensitization of the memory effect due to the photocurrent induced by the high electric field in the selenium film.

The polarized memory effect (the memory in which switching between ON and OFF states depends on the polarity of the bias voltage) on the Se-SnO2 system is described. This effect is observed on the samples with Se films 300∼5000 Å in thickness. The ratio of the resistance of OFF state R O F F to that of ON state R O N is about three orders of magnitude. In the case of the film with thickness 103 Å, the threshold voltage from OFF to ON states V t h is 15 V, and the reverse voltage from ON to OFF states V r is 3.5 V.