Electrons and phonons in single layers of hexagonal indium chalcogenides from ab initio calculations

By V. Zólyomi, N. Drummond, Vladimir Fal'ko. 2014

257 citations recorded by the source corpus.

We use density functional theory to calculate the electronic band structures, cohesive energies, phonon dispersions, and optical absorption spectra of two-dimensional In2X2 crystals, where X is S, Se, or Te. We identify two crystalline phases (alpha and beta) of monolayers of hexagonal In2X2, and show that they are characterized by different sets of Raman-active phonon modes. We find that these materials are indirect-band-gap semiconductors with a sombrero-shaped dispersion of holes near the valence-band edge. The latter feature results in a Lifshitz transition (a change in the Fermi-surface topology of hole-doped In2X2) at hole concentrations n(S) = 6.86 x 10(13) cm(-2), n(Se) = 6.20 x 10(13) cm(-2), and n(Te) = 2.86 x 10(13) cm(-2) for X= S, Se, and Te, respectively, for alpha-In2X2 and n(S) = 8.32 x 10(13) cm(-2), n(Se) = 6.00 x 10(13) cm(-2), and n(Te) = 8.14 x 10(13) cm(-2) for beta-In2X2.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/8d445496fcb14852b6316a5962be264ed6f72b90

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Production and processing of graphene and related materials (2020, background): “1 m2 V−1 s−1) and an interesting ‘Mexican hat’ valence band energy dispersion [1109–1113], sensitive to the layer thickness [1110, 1111, 1113] and/or an externally applied electric field [1109].”