Abstract: A method of alternating current potential drop measurement is provided in which the flow of the current in the specimen is laterally confined by passing the applied current externally over and in the immediate proximity to the surface of the specimen. To this end, a voltage probe is provided having a longitudinally extending isolated conductor which is connected to one current contact of a pair of current contacts. In use, this is arranged to provide an external flow path for current applied to the specimen. The isolated conductor is arranged to lie adjacent to the voltage probe contacts. For convenience of mounting, the conductor may be implemented as a conductive track on a printed circuit board. The track may also be bifurcated in order to accommodate one or more short lengths of conductor which can be used to form one or more compensating inductive loops which latter may be wired to afford cancellation of picked-up induced emf.

Abstract: Precursor (9) is atomized by being ionized (11,12) and is then vaporized (14) prior to deposition. The ionized vapor is controlled by electrodes (2,15) to control its flow and/or its deposition on a substrate.