Variable-temperature scanning tunneling microscope

Abstract

A thermally compensated tube scanner scanning tunneling microscope (STM) has been constructed and successfully tested. This design utilizes two concentric piezoelectric tubes, one for scanning and one for thermal compensation and inertial sample translation (over several mm), as well as fine adjustment of sample position while in tunneling range. This design eliminates the need for mechanical components such as springs, levers, gears, or stepper motors that are known to result in considerable vibration sensitivity, thermal drift, and low-resonance frequencies. This new design demonstrates continuously variable-temperature operation as well as atomic resolution without vibration isolation for the first time in a STM. Thermal drift of less than 1 Å/h and less than 10 Å/K have been determined. Also, the lowest mechanical resonance frequency of 21 kHz makes this new design suitable for high-speed applications such as video rate scanning.

Characterization of nanometer-sized, mechanically exfoliated graphene on the H-passivated Si(100) surface using scanning tunneling microscopy

“…Our experiments were conducted using a homebuilt room temperature ultra-high vacuum scanning tunnelling microscope (UHV-STM) at a base pressure of 5×10 -11 Torr [22]. In our experimental setup, the bias voltage is applied to the sample and the tip is grounded through a current preamplifier.…”

Scanning probe energy loss spectroscopy below 50nm resolution

“…1(f) we are looking at electrons of decreasing kinetic energy, i.e., we are moving from the elastic peak region of the spectrum through the energy-loss features associated with plasmon and interband excitations 11-17 until we finally reach the low-energy secondary electrons emitted from the surface. We have previously reported images 6,18 in which the total yield of backscattered (and secondary) electrons was recorded while scanning across the surface, and shown that in this case the image contrast depends on shadowing effects and edge enhancement arising from the surface topography. 18 The individual images shown in Fig.…”

“…The SPELS instrument employed in this study employed a STM head based on the "pocket size" STM design of Lyding and others, [6][7][8] which provides good access to the sample surface. The STM tips were produced by etching a 0.5 mm polycrystalline tungsten wire in a two-molar solution of NaOH; the tips were cleaned in situ by electron bombardment heating, and sharpened by argon ion sputtering.…”

Field-directed sputter sharpening for tailored probe materials and atomic-scale lithography

“…Passivation and STM are performed in an UHV chamber with a background pressure below 1 × 10 − 10 Torr. Scanning and patterning are performed at room temperature in a home-built UHV-STM system 37 . Th e Si(100) 2 × 1:H surface is prepared by overnight degas at 600 ° C followed by three 1,250 ° C fl ashes (30 s, 10 s, 5 s) and passivated by atomic hydrogen generated at a 1,300 ° C tungsten fi lament in a hydrogen background (2 × 10 − 6 Torr).…”