Local electronic structure of stable monolayers of α-MoO3−x grown on graphite substrate

Dorota A. Kowalczyk, Maciej Rogala, Karol Szałowski, Witold Kozłowski, Iaroslav Lutsyk, Michał Piskorski, Paweł Krukowski, Paweł Dabrowski, Domagoj Belić, Michał Cichomski, Zbigniew Kłusek, Paweł J. Kowalczyk

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review

Sammanfattning

We report on van der Waals epitaxy of two-dimensional (2D) molybdenum trioxide (MoO3−x) with monolayer thickness directly grown on highly oriented pyrolytic graphite by thermal evaporation under ultrahigh vacuum. The chemical composition, electronic and crystalline lattice structures of the mono-and few-layer MoO3−x sheets are analysed. Using scanning tunnelling microscopy and spectroscopy, we investigate the electronic properties of MoO3−x as a function of the number of layers and measure the apparent energy gap to be 0.4 eV for the first three layers of MoO3−x on graphite. We carried out density functional theory calculations to shed light on the mechanism underlying the observed narrow bandgap with oxygen deficiency. Moreover, the air exposure effect on monolayer MoO3−x is investigated confirming that the apparent bandgap closes, and additionally we show the reduction of the work function from 5.7 to 4.7 eV. We prove that it is possible to synthesize the 2D, non-stoichiometric, and electrically conductive MoO3−x.

Originalspråkengelska
Artikelnummer025005
Tidskrift2D Materials
Volym8
Utgåva2
DOI
StatusPublished - 2021

Ämnesklassifikation (UKÄ)

  • Den kondenserade materiens fysik
  • Materialkemi

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