Quantitative measurement of electric properties on the nanometer scale using atomic force microscopy

We describe a method to measure capacitances and dopant densities with a nanometer scale spatial resolution. It is implemented using an atomic force microscope with a conductive tip interfaced with a microwave vector network analyzer. A microwave signal is sent to the tip and the ratio of reflected and incident wave is measured. The technique - also referred to as scanning microwave microscopy (SMM) - can be calibrated to yield quantitative measurements of the capacitance at the tip sample junction. On semiconductor surfaces SMM can be used to measure dopant density distribution quantitatively.