Design and performance of a beetle-type double-tip scanning tunneling microscope (original) (raw)
Related papers
A simple, ultrahigh vacuum compatible scanning tunneling microscope for use at variable temperatures
Review of Scientific Instruments, 1996
We present the construction of a very compact scanning tunneling microscope ͑STM͒ which can be operated at temperatures between 4 and 350 K. The tip and a tiny tip holder are the only movable parts, whereas the sample and the piezoscanner are rigidly attached to the body of the STM. This leads to an excellent mechanical stability. The coarse approach system relies on the slip-stick principle and is operated by the same piezotube which is used for scanning. As an example of the performance of the device, images of a NbSe 2 surface with atomic resolution are obtained.
A scanning tunneling microscopy tip with a stable atomic structure
Metals and Materials International, 2004
A single stable adatom on a {110}-type plane of a tungsten tip is created via field-evaporation in a fieldion microscope (FIM) operating at room temperature. This single adatom has sufficient surface mobility at room temperature and migrates, in one-dimension, along a <111>-type direction toward an edge of a {110}-type plane, due to the existence of an electric field gradient. The plane edge has a higher local electric field than its center, since it has a higher local geometric curvature. This result implies that the stable position of a single adatom during a scan of a scanning tunneling microscope (STM) tip on a surface is at the edge and not at the center of a {110}-type plane at room temperature. Therefore, the electron wave function of a tip is not symmetric and this fact should be taken into account in a careful analysis of STM images. Also a tip with a dislocation emerging at a {110}-type plane is suggested as an improved STM tip configuration, as the step at the surface, created by the intersection of the dislocation with it, is a perpetual source of single adatoms.
A 30 mK, 13.5 T scanning tunneling microscope with two independent tips
We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.
A scanning tunneling microscope with a wide sampling range
Review of Scientific Instruments, 1990
C{)n~truction of a simple scanning tunneling microscope (STM) is described. This STM is suitable for atmospheric, controiled atmosphere, and high vacuum (but not UHV) work. This STM is especially wen suited for determining surface topography on the 0.1 nm scale when images must be obtained over a wide sampling region (mm). Interchangeable piezo heads allow the STM to be used either for atomic resolution or for large (800 X 800 urn) area scans. Atomic resolution pictures of the graphite surface demonstrate that this design is suitable for use with structures smaller than 0.1 nm. An image of a thin film of Au, deposited on pyrex, is also presented.
Four-probe measurements with a three-probe scanning tunneling microscope
Review of Scientific Instruments, 2014
We present an ultrahigh vacuum (UHV) three-probe scanning tunneling microscope in which each probe is capable of atomic resolution. A UHV JEOL scanning electron microscope aids in the placement of the probes on the sample. The machine also has a field ion microscope to clean, atomically image, and shape the probe tips. The machine uses bare conductive samples and tips with a homebuilt set of pliers for heating and loading. Automated feedback controlled tip-surface contacts allow for electrical stability and reproducibility while also greatly reducing tip and surface damage due to contact formation. The ability to register inter-tip position by imaging of a single surface feature by multiple tips is demonstrated. Four-probe material characterization is achieved by deploying two tips as fixed current probes and the third tip as a movable voltage probe.
2007
We describe the design and performance of a fast-scanning, variable temperature scanning tunneling microscope ͑STM͒ operating from 80 to 700 K in ultrahigh vacuum ͑UHV͒, which routinely achieves large scale atomically resolved imaging of compact metallic surfaces. An efficient in-vacuum vibration isolation and cryogenic system allows for no external vibration isolation of the UHV chamber. The design of the sample holder and STM head permits imaging of the same nanometer-size area of the sample before and after sample preparation outside the STM base. Refractory metal samples are frequently annealed up to 2000 K and their cooldown time from room temperature to 80 K is 15 min. The vertical resolution of the instrument was found to be about 2 pm at room temperature. The coarse motor design allows both translation and rotation of the scanner tube. The total scanning area is about 8 ϫ 8 m 2 . The sample temperature can be adjusted by a few tens of degrees while scanning over the same sample area.
Manipulation of Atoms and Molecules with the Low-Temperature Scanning Tunneling Microscope
Japanese Journal of Applied Physics, 2001
The controlled manipulation with a scanning tunneling microscope (STM) down to the scale of small molecules and single atoms allows the buildup of molecular and atomic nanostructures. In the case of the lateral manipulation of adsorbed species, in which only tip/particle forces are used, three different manipulation modes (pushing, pulling, sliding) can be discerned. Vertical manipulation of Xe and CO is demonstrated, leading to the formation of functionalized tips, which can be used for improved imaging and even to perform vibrational spectroscopy on single molecules. Furthermore, we describe how we have reproduced a full chemical reaction with single molecules, whereby all basic steps, namely, preparation of the reactants, diffusion and association, are induced with the STM tip.
SCANNING TUNNELING MICROSCOPE COMBINED WITH A SCANNING ELECTRON-MICROSCOPE
Review of Scientific Instruments, 1986
We have developed a small scanning tunneling microscope (STM) to be incorporated into a scanning electron microscope (SEM). Vibration isolation and damping is achieved solely with Viton dampers. As a stand-alone unit, a tunnel-gap stability of about 1 A is reached at atmospheric air pressure without additional sound protection. Stability improves by at least an order of magnitude when incorporated into a SEM.
Tunneling tips imaged by scanning tunneling microscopy
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1990
Electrochemically etched tips commonly used for scanning tunneling microscopy (STM) have been investigated by STM itself. By appropriate positioning, the topography of the apex of the tips could be investigated, leading to a typical value for the tip radius of 300 nm. Different techniques have been attempted to untangle the convoluted STM image. By rotating one tip relative to the other, or by exchanging one tip and leaving the other in place, some distinct features can be attributed to the one or the other tip. Furthermore, the profile of the tip could be investigated by scanning over the edge of a cleaved crystal. Beside the fundamental interest in the tip structure itself, this configuration offers the unique feature of unambiguous relocation of the scanned area when the tip investigated in that experiment has been removed and reinstalled to the microscope.