Persistent photoconductivity in two-dimensional Mo1-xWxSe2-MoSe2 van der Waals heterojunctions

Xufan Li, Ming Wei Lin, Alexander A. Puretzky, Leonardo Basile, Kai Wang, Juan C. Idrobo, Christopher M. Rouleau, David B. Geohegan, Kai Xiao

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Van der Waals (vdW) heterojunctions consisting of vertically-stacked individual or multiple layers of two-dimensional layered semiconductors, especially the transition metal dichalcogenides (TMDs), show novel optoelectronic functionalities due to the sensitivity of their electronic and optical properties to strong quantum confinement and interfacial interactions. Here, monolayers of n-type MoSe2 and p-type Mo1-xW xSe2 are grown by vapor transport methods, then transferred and stamped to form artificial vdW heterostructures with strong interlayer coupling as proven in photoluminescence and low-frequency Raman spectroscopy measurements. Remarkably, the heterojunctions exhibit an unprecedented photoconductivity effect that persists at room temperature for several days. This persistent photoconductivity is shown to be tunable by applying a gate bias that equilibrates the charge distribution. These measurements indicate that such ultrathin vdW heterojunctions can function as rewritable optoelectronic switches or memory elements under time-dependent photo-illumination, an effect which appears promising for new monolayer TMDs-based optoelectronic devices applications.

Original languageEnglish
Pages (from-to)923-930
Number of pages8
JournalJournal of Materials Research
Volume31
Issue number7
DOIs
StatePublished - Apr 14 2016

Funding

Synthesis science sponsored by the Materials Science and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy. Materials characterization conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. L.B. acknowledges the financial support of the National Secretariat of Higher Education, Science, Technology and Innovation of Ecuador (SENESCYT). X.L. and M.L. acknowledge support from ORNL Laboratory Directed Research and Development.

Keywords

  • crystal
  • optoelectronic
  • photoconductivity

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