Atomic resolution imaging at 2.5 GHz using near-field microwave microscopy

Atomic resolution imaging is demonstrated using a hybrid scanning tunneling/near-field microwave microscope. The microwave channels of the microscope correspond to the resonant frequency and quality factor of a coaxial microwave resonator, which is built in to the scan head. The microscope is capable of simultaneously recording the low frequency tunnel current (0–10 kHz) and the information from the microwave channels. When the tip-sample distance is within the tunneling regime, we obtain atomic resolution images using the microwave channels. We attribute this atomic contrast to gigahertz frequency current through the tunnel junction. Images of graphite and Au(111) are presented.