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arXiv · 1511.02255

Iso-oriented monolayer {\alpha}-MoO3(010) films epitaxially grown on SrTiO3(001)

Yingge Du·Guoqiang Li·Erik W. Peterson·Jing Zhou·Xin Zhang·Rentao Mu·Zdenek Dohnálek·Mark Bowden·Igor Lyubinetsky·Scott A. Chambers
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Abstract

The ability to synthesis well-ordered two-dimensional materials under ultra-high vacuum and directly characterize them by other techniques in-situ can greatly advance our current understanding on their physical and chemical properties. In this paper, we demonstrate that iso-oriented {\alpha}-MoO3 films with as low as single monolayer thickness can be reproducibly grown on SrTiO3(001) (STO) substrates by molecular beam epitaxy ( (010)MoO3 || (001)STO, [100]MoO3 || [100]STO or [010]STO) through a self-limiting process. While one in-plane lattice parameter of the MoO3 is very close to that of the SrTiO3 (aMoO3 = 3.96 {\AA}, aSTO = 3.905 {\AA}), the lattice mismatch along other direction is large (~5%, cMoO3 = 3.70 {\AA}), which leads to relaxation as clearly observed from the splitting of streaks in reflection high-energy electron diffraction (RHEED) patterns. A narrow range in the growth temperature is found to be optimal for the growth of monolayer {\alpha}-MoO3 films. Increasing deposition time will not lead to further increase in thickness, which is explained by a balance between deposition and thermal desorption due to the weak van der Waals force between {\alpha}-MoO3 layers. Lowering growth temperature after the initial iso-oriented {\alpha}-MoO3 monolayer leads to thicker {\alpha}-MoO3(010) films with excellent crystallinity.

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Yingge Du, Guoqiang Li, Erik W. Peterson, Jing Zhou, Xin Zhang, Rentao Mu, Zdenek Dohnálek, Mark Bowden, Igor Lyubinetsky, Scott A. Chambers. 2015-11-06. Iso-oriented monolayer {\alpha}-MoO3(010) films epitaxially grown on SrTiO3(001). https://doi.org/10.1039/c5nr07745a

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