Cryogenic variable temperature ultrahigh vacuum scanning tunneling microscope

Foley, E. T.; Kam, A. F.; Lyding, Joseph W.

doi:10.1063/1.1287046

Cited by 14 publications

(5 citation statements)

References 17 publications

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“…In addition to fliping the rotator, it can easily interconvert among three pairs of enantiomeric structures even well below room temperature. We had access to an ultrahigh-vacuum (UHV) low-temperature STM , that allowed us to obtain the images on gold at 78 K. They offered no better resolution than those taken under ambient conditions, but it is possible that the molecules were obscured by the adsorption of adventitious water. Ideally, one would want to bake the sample under UHV conditions to rid the substrate of water, but XP spectra of samples that were heated under UHV showed adsorbed 2 to be unstable at temperatures above ∼360 K, leading us to abandon further efforts to obtain low-temperature STM images.…”

Section: Discussionmentioning

confidence: 99%

Mercury-Mediated Attachment of Metal-Sandwich-Based Altitudinal Molecular Rotors to Gold Surfaces

et al. 2010

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Gold surface attachment of altitudinal molecular rotors provided with ten -HgSCH 2 CH 2 SCH 3 "tentacles" has been monitored with ellipsometry, scanning tunneling microscopy, and X-ray photoelectron spectroscopy (XPS). The rotors appear to adsorb on the gold surface in the intended orientation, with rotor axle parallel to the surface, without any inclination for multilayer growth. According to XPS data, the sulfur-containing tentacles start to be detectably oxidized within hours of exposure to air and can be ultimately removed by washing. The rotor molecules nevertheless remain firmly attached in the desired orientation, apparently due to a direct interaction of their Hg atoms with the gold surface. When the tentacles are simplified to -HgOCOCF 3 substituents, the molecules adhere to the surface as well, but not always in the desired orientation.

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Section: Discussionmentioning

confidence: 99%

Mercury-Mediated Attachment of Metal-Sandwich-Based Altitudinal Molecular Rotors to Gold Surfaces

et al. 2010

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“…Hydrogen and deuterium desorption measurements were performed using a liquid-He-cooled UHV STM [7]. Highly doped n-type Si(100) samples (As-doped 0.005 V cm) were used in order to maintain good substrate conductivity at a low temperature.…”

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confidence: 99%

Cryogenic UHV-STM Study of Hydrogen and Deuterium Desorption from Si(100)

et al. 1998

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A cryogenic UHV scanning tunneling microscope has been used to study the electron stimulated desorption of hydrogen and deuterium from Si(100) surfaces at 11 K. A strong isotope effect is observed, as seen previously at room temperature. Above ϳ5 eV, the desorption yields for H and D are temperature independent, while in the tunneling regime, below 4 eV, H is a factor of ϳ300 easier to desorb at 11 than at 300 K. This large temperature dependence is explained by a model that involves multiple vibrational excitation and takes into account the increase of the Si-H(D) vibrational lifetime at low temperature. [S0031-9007(97)

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“…9 Hence, there has been much interest and effort toward developing STM systems and SP-STM systems in cryogenic superconducting magnetic fields. [10][11][12][13][14][15][16][17][18][19][20] In terms of materials, semiconductors and semiconductor based structures play crucial roles in electronic, optoelectronic, and spintronic applications. For example, ferromagnet/semiconductor hetero-structures are used for injection of spin-polarized currents into semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy

Lin

Foley

Alam

et al. 2014

Review of Scientific Instruments

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Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without breaking vacuum, and convenient visual access to the sample and tip inside a superconducting magnet cryostat. A sample/tip handling system is optimized for both the molecular beam epitaxy growth system and the scanning tunneling microscope system. The sample/tip handing system enables in situ STM studies on epitaxially grown samples, and tip exchange in the superconducting magnet cryostat. The hybrid molecular beam epitaxy and low temperature scanning tunneling microscopy system is capable of growing semiconductor-based hetero-structures with controlled accuracy down to a single atomic-layer and imaging them down to atomic resolution.

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Cryogenic variable temperature ultrahigh vacuum scanning tunneling microscope

Cited by 14 publications

References 17 publications

Mercury-Mediated Attachment of Metal-Sandwich-Based Altitudinal Molecular Rotors to Gold Surfaces

Mercury-Mediated Attachment of Metal-Sandwich-Based Altitudinal Molecular Rotors to Gold Surfaces

Cryogenic UHV-STM Study of Hydrogen and Deuterium Desorption from Si(100)

Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy

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