Thermodynamic properties of scandium carbides

Sidorko, V. R.; Goncharuk, L. V.; Gordiychuk, O.V.; Antonchenko, R.V.

doi:10.1016/0925-8388(95)01701-1

Cited by 10 publications

(2 citation statements)

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“…After depositing 3.2 nm Sc, a carbidic chemical state is detected at ~281.6 eV in the corresponding C 1s core level is detected at 281.60 eV (figure S5), which corroborates the presence of a small concentration of ScC. The formation of Sc-C bonds is exothermic at RT (∆G • f ,ScC = −164 kJ mol −1 ) [42], which suggests ScC is present during initial deposition steps, but below the limit of XPS detection until a total of 3.2 nm Sc is deposited. The BE of the chemical state (~396.5 eV) detected after depositing > 3 nm Sc and throughout subsequent UHV anneals (figure 2(b)) is in good agreement with the ScN chemical state in the N 1s core level reported previously [43] and the ScN reference film grown in this work (figure S6).…”

Section: Complete Sc Oxidation At Elevated Temperatures In Uhvsupporting

confidence: 53%

Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes

et al. 2019

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Sc has been employed as an electron contact to a number of two-dimensional (2D) materials (e.g. MoS2, black phosphorous) and has enabled, at times, the lowest electron contact resistance. However, the extremely reactive nature of Sc leads to stringent processing requirements and metastable device performance with no true understanding of how to achieve consistent, high-performance Sc contacts. In this work, WSe2 transistors with impressive subthreshold slope (109 mV dec−1) and I ON/I OFF (106) are demonstrated without post-metallization processing by depositing Sc contacts in ultra-high vacuum (UHV) at room temperature (RT). The lowest electron Schottky barrier height (SBH) is achieved by mildly oxidizing the WSe2 in situ before metallization, which minimizes subsequent reactions between Sc and WSe2. Post metallization anneals in reducing environments (UHV, forming gas) degrade the I ON/I OFF by ~103 and increase the subthreshold slope by a factor of 10. X-ray photoelectron spectroscopy indicates the anneals increase the electron SBH by 0.4–0.5 eV and correspondingly convert 100% of the deposited Sc contacts to intermetallic or scandium oxide. Raman spectroscopy and scanning transmission electron microscopy highlight the highly exothermic reactions between Sc and WSe2, which consume at least one layer RT and at least three layers after the 400 °C anneals. The observed layer consumption necessitates multiple sacrificial WSe2 layers during fabrication. Scanning tunneling microscopy/spectroscopy elucidate the enhanced local density of states below the WSe2 Fermi level around individual Sc atoms in the WSe2 lattice, which directly connects the scandium selenide intermetallic with the unexpectedly large electron SBH. The interface chemistry and structural properties are correlated with Sc–WSe2 transistor and diode performance. The recommended combination of processing conditions and steps is provided to facilitate consistent Sc contacts to WSe2.

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Section: Complete Sc Oxidation At Elevated Temperatures In Uhvsupporting

confidence: 53%

Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes

et al. 2019

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“…In Table I, we summarize a list of previous works on experimental synthesis of topological electrides studied in our paper. We note that the previous experimental works on the synthesis of Sc 2 C reported cubic structure [64][65][66], while theoretical works including our paper and Ref. [45] report the trigonal structure (R3m) as the stable structure.…”

Section: Appendix C: Molecules On the Sc 2 C Surfacementioning

confidence: 52%

Electrides as a New Platform of Topological Materials

et al. 2018

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Recent discoveries of topological phases realized in electronic states in solids have revealed an important role of topology, which ubiquitously appears in various materials in nature. Many well-known materials have turned out to be topological materials, and this new viewpoint of topology has opened a new horizon in material science. In this paper we find that electrides are suitable for achieving various topological phases, including topological insulating and topological semimetal phases. In the electrides, in which electrons serve as anions, the bands occupied by the anionic electrons lie near the Fermi level, because the anionic electrons are weakly bound by the lattice. This property of the electrides is favorable for achieving band inversions needed for topological phases, and thus the electrides are prone to topological phases. From such a point of view, we find many topological electrides, Y 2 C (nodal-line semimetal (NLS)), Sc 2 C (insulator with π Zak phase), Sr 2 Bi (NLS), HfBr (quantum spin Hall system), and LaBr (quantum anomalous Hall insulator), by using ab initio calculation. The close relationship between the electrides and the topological materials is useful in material science in both fields.

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The scandium-titanium-carbon phase diagram

Artyukh

Hyenko

Velikanova

1996

JPE

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Thermodynamic properties of scandium carbides

Cited by 10 publications

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Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes

Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes

Electrides as a New Platform of Topological Materials

The scandium-titanium-carbon phase diagram

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Thermodynamic properties of scandium carbides

Cited by 10 publications

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Engineering the interface chemistry for scandium electron contacts in WSe2 transistors and diodes

Engineering the interface chemistry for scandium electron contacts in WSe2 transistors and diodes

Electrides as a New Platform of Topological Materials

The scandium-titanium-carbon phase diagram

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Product

Resources

About

Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes

Engineering the interface chemistry for scandium electron contacts in WSe₂ transistors and diodes