Design and Construction of a Scanning Tunneling Microscope for Atomic Scale Imaging of Surfaces in Ultra-High Vacuum

The outer layer of atoms of most materials either relax or reconstruct, which often results in a change in the electronic, magnetic, and/or chemical properties. Therefore, we have designed and constructed a scanning tunneling microscope (STM) for use in an ultra-high vacuum (UHV) based surface analysis system in the Surface Science Laboratory at Texas State. The instrument is capable of producing atomic-scale images on single crystal samples and allows transfer of samples to the horizontal manipulator of the system for surface preparation and high-resolution electron energy loss spectroscopy (HREELS) measurements. The main body of STM is constructed from Macor, which is UHV compatible and has a high strength to weight ratio, low thermal expansion coefficient, and low thermal conductivity. The instrument is mounted with springs with a 16'' expansion length and has a resonant frequency of $\sim $1 Hz. The tube scanner is mounted to a UHV compatible inchworm for coarse approach. Custom designed analog electronics and software are used to control the instrument.