Contact Charging and Surface Charge Measurement Using a Scanning Kelvin Technique

This study describes the deposition and recording of surface charges on polyimide with a scanning Kelvin probe microscope. The apparatus used here works with a needle tip whose movements and oscillations are controlled and driven by an electromechanical system. To deposit charges the probe tip touches down to the insulator surface and with an external voltage the contact charging is performed. After the charge deposition the same system works as a vibrating scanning Kelvin probe to measure the charged surface area. This Kelvin probe system has the advantage of a controlled tip oscillation compared to a conventional AFM probe with a free oscillating cantilever. Electrostatic forces cannot stick the tip to the surface. In an additional experiment the charges deposited around an electrode as known from Lichtenberg figures are detected.