Surface
Analysis Unit
Surface
Analysis Unit(Person in Charge: Sidney Cohen)
The surface analysis group provides the means for a variety of surface-sensitive measurements. These include chemical composition of the exposed atomic layers, atomic scale surface topography, electronic and mechanical surface properties, and detection of adsorbed molecules.The various units of this group are housed in two laboratories and include facilities for rudimentary sample preparation and cleaning, such as ozone cleaner, clean hood, and so forth.
The Ultrahigh Vacuum Unit is a multifaceted system for surface analyses at pressures below 10-9 torr. The main analysis chamber includes a Kratos Axis HS photoelectron spectrometer, which detects elements and determines their chemical state on the surface at depths up to 3 nm with sensitivity of 0.1%. The system includes an ultraviolet lamp for valence band measurements, monochromator for high resolution work, ion gun for sputtering the surface, and flood gun for insulating samples. In addition, an electron gun for performing electron energy loss spectroscopy has been installed. A second vacuum chamber attached to the analysis chamber contains a VG Low Energy Electron Diffractometer to determine the surface crystalline state.
The Scanned Probe Microscopy Unit contains three separate scanning tunneling/scanning force microscopes (Digital Instruments Nanoscope, NT-MDT P47/LS and NTEGRA) that enable determination of surface topography and mechanical and electrical properties at resolutions ranging from tens of microns down to atomic scale. Liquid cells,heated/cooled stages, and a gas inlet allow working in different media and under controlled temperature and humidity.