Surface resistivity measurements on insulators and semiconductors in vacuum

Full text: Surface resistivity is an important property of materials of technological interest like insulators and semiconductors. This paper describes a new technique for resistivity measurement in the surface region of such materials, recently innovated to a vacuum environment, an improvement to the former system, which has been shown to be successful under atmospheric conditions. The experimental measurement involves the adaptation of a surface charge decay technique to allow the straightforward determination of the electrical resistivity in the surface region. The measurements to be carried out under vacuum will allow reduced sample contamination as well as measurement of surface treated or coated samples. The new system comprises: 1. An high vacuum, cylindrically symmetric planar capacitor arrangement. 2. Two manipulators, which translate and orient the sample and an adjacent capacitive electrode for coupling to an electrometer. 3. A custom designed electron gun, which allows sample charging by secondary electron emission. (Simulations of the electron lens trajectories were performed using SIMION 3D.). 4. A data acquisition and control package is used as it provides a combined hardware and software for the transfer of charge decay data directly from the electrometer to a PC. Preliminary measurements have commenced for surface resistivity measurements of the following insulator materials: glass, Perspex and polyethene. Theoretical analysis of surface charge transport is also being undertaken. Future investigations will involve diamond films and semiconductors, for which fast switching of charge discharge cycles will be developed