Visualization of tip-surface geometry at atomic distance by TEM-STM holder

Abstract

To clarify the tip-surface interaction of the scanning tunneling microscope (STM) by using a UHV transmission electron microscope (TEM), we specially designed a TEM-STM holder. In the present high-resolution electron microscope and diffraction studies, after applying a voltage of 50 V between W-tip and Au-surface at a distance of 70 nm in the feedback control mode of the tunneling current of 0.1 nA, the tip apex which has many protrusions was changed to one with a single protrusion. The tip was found to be cleaned and sharpened to the ideal conical shape. At the tip apex a droplet was generated with the same [110] orientation as the tip. In addition to the sharpening of the tip, a droplet was generated on the Au-specimen surface. Generation of similar protrusions on the tip droplet occurred under applied bias voltage of usual STM operation.