Electrostatic forces between metallic tip and semiconductor surfaces

Atomic force microscopy used in the resonant mode is a powerful tool for measuring local surface properties: for example, the quantitative analysis of the electrical forces induced by the application of an electric field between a conductive microscope tip and a surface allows the determination of the tip/surface capacitance and the local surface work function. However, these quantitative analyses require knowledge of tip geometry. In this article, we show that the simple procedure of evaluating the tip curvature radius by fitting the variations of the electrostatic force with the tip-surface distance is not always adapted to the case where one of the tip-surface system elements is a semiconductor. However, particular experimental conditions are determined to overcome these difficulties.