THE COAXIAL TIP AS A NANO-ANTENNA FOR SCANNING NEAR-FIELD MICROWAVE TRANSMISSION MICROSCOPY

A novel scanning-probe setup is reported that maps the complex transmi ssion of microwaves. Response to topographic features as small as 15 n m was observed. The sharpened coaxial probe tip serves as a microwave antenna and, at the same time, as a tunnel tip to warrant precise dist ance control by STM (scanning tunneling microscope) feedback. The inst rument can be applied to map the microwave conductivity of, e.g. thin films or low-dimensional semiconductors. Consequences for the developm ent of an infrared microscope are outlined. (C) 1997 Elsevier Science Ltd.