A simple design for a four-point probe suitable for precision surface conductivity measurements is described. Our design makes use of small, commercially available spring contact probes which are mounted in a custom built MACOR ceramic probe head. The design is suitable for use in ultrahigh vacuum applications, and the custom-built parts can be fabricated in any machine shop. Very reproducible values were obtained using this probe for surface conductivity measurements on a MoS2(0001) model catalyst, a sputter deposited indium-tin oxide thin film and a doped silicon wafer. |