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Issue 12, 2017
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An origin of unintentional doping in transition metal dichalcogenides: the role of hydrogen impurities

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Abstract

We theoretically elucidate the origin of unintentional doping in two-dimensional transition-metal dichalcogenides (TMDs), which has been consistently reported by experiment, but which still remains unclear. Our explanation is based on the charge transfer between TMDs and the underlying SiO2 in which hydrogen impurities with a negative-U property pin the Fermi level of the SiO2 as well as adjacent TMD layers. Using first-principles calculations, we obtain the pinning point of the Fermi level from the charge transition level of the hydrogen in the SiO2, ε(+/−), and align it with respect to the band-edge positions of monolayer TMDs. The computational results show that the Fermi levels of TMDs estimated by ε(+/−) successfully explain the conducting polarity (n- or p-type) and relative doping concentrations of thin TMD films. By enlightening on the microscopic origin of unintentional doping in TMDs, we believe that the present work will contribute to precise control of TMD-based electronic devices.

Graphical abstract: An origin of unintentional doping in transition metal dichalcogenides: the role of hydrogen impurities

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Publication details

The article was received on 02 Nov 2016, accepted on 28 Feb 2017 and first published on 01 Mar 2017


Article type: Paper
DOI: 10.1039/C6NR08555E
Citation: Nanoscale, 2017,9, 4265-4271
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    An origin of unintentional doping in transition metal dichalcogenides: the role of hydrogen impurities

    Y. Kang and S. Han, Nanoscale, 2017, 9, 4265
    DOI: 10.1039/C6NR08555E

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