Microwave impedance of a tunnel junction in the theory of a near-field microscope with atomic resolution

Abstract

A theory is constructed for a near-field microwave microscope operating under tunneling breakdown between a probe and a conducting sample. Its informative characteristics are determined by the probe impedance, which is formed from the capacitive impedance Z_p of the near-field probe–sample interaction and tunnel junction impedance Z_t. A technique whereby the impedance Z_p is calculated using coaxial geometry of the probe is developed. Some properties of the impedance Z_t defined via the developed theory and published experimental data are investigated.