Scanning surface harmonic microscopy: Scanning probe microscopy based on microwave field-induced harmonic generation

A scanning probe microscope has been integrated into a microwave resonator tunable from 2.2 to 3.4 GHz with a quality factor Q larger than 1000. Nonlinear phenomena caused generation of higher harmonics when rf fields in the range of 109 V/m were applied between tip and sample. Higher harmonic signals were detected at a bandwidth of 10 kHz on conductor surfaces as well as on thin insulating films and were used as feedback to the control loop for imaging graphite surface features and oxidized silicon surfaces with subnanometer resolution.