Micro Kelvin probe for local work-function measurements

This article describes a miniaturized Kelvin probe with a lateral resolution of 40 μm. Applied to a conducting or semiconducting surface, it allows a microscopic imaging of the difference of the work functions between the Kelvin probe and a sample. The signal resolution is better than 6 mV with an integration time of 300 to 400 ms, which is sufficient for most of the applications. The necessary steps to optimize the signal processing are described in detail.