UHV Scanning Tunneling Microscopy

Scanning tunneling microscopy (STM) provides key information on the structure and electronic properties of the surfaces of materials. Our UHV STM is a versatile instrument that combines STM with other ways to probe or measure the sample. UHV conditions allow clean surfaces to be prepared. A side chamber enables deposition of metals onto the sample within the same vacuum system. The STM itself is a four-probe system. Scanning tunneling microscopy and spectroscopy can be carried out with any one of the four tips, and another tip can be used to contact samples such as isolated flakes of 2D materials. Furthermore, measurements are possible such as surface potential mapping, where two tips are placed on the sample, current flows between them, and a third tip measures local changes in surface potential. A scanning electron microscope is integrated within the system so that probe positions and voltage contrast can be measured. Finally, a mass-filtered focused ion beam source placed above the sample allows patterning of the surface with ions such as Si⁺, Si²⁺, Au³⁺ and Ge⁺ while under vacuum.