Observation of Switchable Photoresponse of a Monolayer WSe2-MoS2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging

Youngwoo Son, Ming Yang Li, Chia Chin Cheng, Kung Hwa Wei, Pingwei Liu, Qing Wang, Lain Jong Li, Michael S. Strano

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

In the pursuit of two-dimensional (2D) materials beyond graphene, enormous advances have been made in exploring the exciting and useful properties of transition metal dichalcogenides (TMDCs), such as a permanent band gap in the visible range and the transition from indirect to direct band gap due to 2D quantum confinement, and their potential for a wide range of device applications. In particular, recent success in the synthesis of seamless monolayer lateral heterostructures of different TMDCs via chemical vapor deposition methods has provided an effective solution to producing an in-plane p-n junction, which is a critical component in electronic and optoelectronic device applications. However, spatial variation of the electronic and optoelectonic properties of the synthesized heterojunction crystals throughout the homogeneous as well as the lateral junction region and the charge carrier transport behavior at their nanoscale junctions with metals remain unaddressed. In this work, we use photocurrent spectral atomic force microscopy to image the current and photocurrent generated between a biased PtIr tip and a monolayer WSe2-MoS2 lateral heterostructure. Current measurements in the dark in both forward and reverse bias reveal an opposite characteristic diode behavior for WSe2 and MoS2, owing to the formation of a Schottky barrier of dissimilar properties. Notably, by changing the polarity and magnitude of the tip voltage applied, pixels that show the photoresponse of the heterostructure are observed to be selectively switched on and off, allowing for the realization of a hyper-resolution array of the switchable photodiode pixels. This experimental approach has significant implications toward the development of novel optoelectronic technologies for regioselective photodetection and imaging at nanoscale resolutions. Comparative 2D Fourier analysis of physical height and current images shows high spatial frequency variations in substrate/MoS2 (or WSe2) contact that exceed the frequencies imposed by the underlying substrates. These results should provide important insights in the design and understanding of electronic and optoelectronic devices based on quantum confined atomically thin 2D lateral heterostructures.

Original languageEnglish (US)
Pages (from-to)3571-3577
Number of pages7
JournalNano Letters
Volume16
Issue number6
DOIs
StatePublished - Jun 8 2016

Fingerprint

Photocurrents
photocurrents
Heterojunctions
Monolayers
optoelectronic devices
Imaging techniques
Optoelectronic devices
transition metals
pixels
electronics
Fourier analysis
Transition metals
p-n junctions
Energy gap
Pixels
photodiodes
heterojunctions
charge carriers
polarity
graphene

Keywords

  • heterostructure
  • MoS
  • photoresponsivity
  • transition metal dichalcogenides
  • Two-dimensional materials
  • WSe

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Observation of Switchable Photoresponse of a Monolayer WSe2-MoS2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging. / Son, Youngwoo; Li, Ming Yang; Cheng, Chia Chin; Wei, Kung Hwa; Liu, Pingwei; Wang, Qing; Li, Lain Jong; Strano, Michael S.

In: Nano Letters, Vol. 16, No. 6, 08.06.2016, p. 3571-3577.

Research output: Contribution to journalArticle

Son, Youngwoo ; Li, Ming Yang ; Cheng, Chia Chin ; Wei, Kung Hwa ; Liu, Pingwei ; Wang, Qing ; Li, Lain Jong ; Strano, Michael S. / Observation of Switchable Photoresponse of a Monolayer WSe2-MoS2 Lateral Heterostructure via Photocurrent Spectral Atomic Force Microscopic Imaging. In: Nano Letters. 2016 ; Vol. 16, No. 6. pp. 3571-3577.
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