A study of the interlayer behaviour by means of the simultaneous application of DC and AC voltages

A promising technique for the investigation of interfacial layers involves the simultaneous application of DC and AC voltages. The application of a DC voltage causes charges to accumulate at the layer boundaries, and the field distribution in the specimen changes with time. This causes the layer resistivity to change also, as it is likely to be field dependent. The AC current caused to flow by the simultaneous application of a small AC voltage ripple is dependent on the ratio of the resistivities of the layer and bulk material. Thus an AC signal can be used as a diagnostic tool for the investigation of the electrical parameters of the interfacial layer. However, although the principle is clear, its application poses some problems. For example, the changes which occur in the specimen are probably quite complicated, but in the absence of detailed information about them, recourse has to be had to representation by a simple model. Such a model, despite deficiencies, can be useful as a starting point from which future refinements can be made