Scanning Tunneling Microscopy
Investigation of nanoscale phenomena often requires experimental approaches extending far beyond conventional techniques, such as highly advanced ultrahigh-vacuum scanning-probe microscopies, including scanning tunneling microscopy, tunneling spectroscopy, and atomic and molecular manipulation.
In the Center for Nanoscale Material's Quantum and Energy Materials (QEM) group, control of materials at the atomic and molecular scale paves the way for breakthroughs in new energy conversion and power-efficient energy technologies. QEM research includes low-dimensional materials such as graphene, borophene and heterostructures formed by stacked two-dimensional materials; single-molecule studies on surfaces; atomic-scale investigations of structural, electronic, magnetic and optical properties of nanostructured surfaces; and atomic and molecular manipulation. Ultrahigh-vacuum scanning-probe microscopies with a variety of extended capabilities are exploited to further this research at the atomic scale.
A variable-temperature (VT) scanning tunneling microscope with atomic force microscopy capabilities (Omicron VT-AFM/STM) operates in an ultrahigh vacuum (UHV) environment with a base pressure of < 1E-10 mbar and 55-400 K. Atomic resolution is routinely obtained at room temperature and below. The AFM capabilities support a range of scanning modes. The analysis chamber also houses a LEED/Auger with an attached preparation chamber for sample cleaning and deposition (e.g., sputter cleaning, direct current heating, e-beam heating stage, metal deposition). For details, contact the instrument custodian.
Also available is a low-temperature ultrahigh vacuum scanning tunneling microscope (4K base with temperature variability) with 6T external magnetic field applied normal to the sample surface. This instrument is intended for variable temperature high impact research requiring an external magnetic field (Omicron Cryo SFM). For details, contact the instrument custodian.
A VT-STM with optical access operates in an UHV environment with a base pressure of < 1E-10 mbar and 55-300 K. Atomic resolution can be obtained at room temperature and below on appropriate samples. The analysis chamber also houses a LEED/Auger with an attached preparation chamber for sample cleaning and deposition (sputter cleaning, direct current heating, e-beam heating stage, metal deposition). For details, contact the instrument custodian.
A low-temperature scanning tunneling microscope/q+ atomic force microscope (LT-STM/q+AFM, Createc) is also available for atomic and molecular manipulation studies and single atom and molecule spectroscopy. Typical operation sample temperature is ~ 5K. The temperature can also be varied from 5 to 25 K and 80 to 100 K. This system is suitable for single atom and molecule tunneling spectroscopy such as dI/dV, d2I/dV2 and dI/dz. The system can be also operated as spin-polarized STM with an internal (vertical) magnetic field of 2.5 T. The base pressure of the system is < 1E-10 mbar and the sample preparation chamber includes sputter cleaning and resistive annealing facilities as well as molecular deposition sources. For details, contact the instrument custodian.