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Anomalous oxidation and its effect on electrical transport originating from surface chemical instability in large area, few-layer 1T′-MoTe2 film

Abstract

Two-dimensional (Mo,W)Te2 film has attracted explosive research interest as electronic device channel material, topological insulator and Weyl semimetal recently. However, one critical concern to hamper their diverse applications is surface chemical instability due to the weak Mo(W)-Te bond energy reflected in the small electronegativity difference between Mo(W) and Te, which fundamentally induce unpredictable surface oxidation and remarkably affect the film quantum transport. Here, for the first time, we clarify an anomalous oxidation featuring an unbalanced oxidation process in large area, few-layer 1T′-MoTe2, which originates from the surface chemical instability. We identify the oxidation temperature, oxygen flow rate, structural polymorphism, and atomic chemical bond electronegativity dominate the preferential surface oxidation, and can be monitored by arising and decomposition of Raman-active Te metalloids. Vitally importantly, we verify the formed ultrathin natural amorphous MoO3-TeO2 surface-layer with an approximate self-limiting thickness significantly affects the transport properties of underlying few-layer 1T′-MoTe2 film. We also reveal a similar oxidation tendency in few-layer 2H-MoTe2 and 1T′-WTe2 but with a higher resistance to oxidation than 1T′-MoTe2 due to their inherent phase stability. Our findings not only represent a solid advance in understanding surface chemical instability of atomically-thin 2D TMDCs materials, but also highlight technically essential importance of constructing ultrathin natural oxide dielectrics/TMDCs interface with a controllable surface oxidation process for atomically-thin TMDCs-based devices.

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Publication details

The article was received on 15 Jul 2018, accepted on 08 Oct 2018 and first published on 08 Oct 2018


Article type: Paper
DOI: 10.1039/C8NR05699D
Citation: Nanoscale, 2018, Accepted Manuscript
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    Anomalous oxidation and its effect on electrical transport originating from surface chemical instability in large area, few-layer 1T′-MoTe2 film

    L. Yang, H. Wu, W. Zhang, Z. Chen, J. Li, X. Lou, Z. Xie, R. Zhu and H. Chang, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR05699D

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