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Microwave near-field imaging of two-dimensional semiconductors.

Authors
Type
Published Article
Journal
Nano Letters
1530-6992
Publisher
American Chemical Society
Publication Date
Volume
15
Issue
2
Pages
1122–1127
Identifiers
DOI: 10.1021/nl504960u
PMID: 25625509
Source
Medline
Keywords
License
Unknown

Abstract

Optimizing new generations of two-dimensional devices based on van der Waals materials will require techniques capable of measuring variations in electronic properties in situ and with nanometer spatial resolution. We perform scanning microwave microscopy (SMM) imaging of single layers of MoS2 and n- and p-doped WSe2. By controlling the sample charge carrier concentration through the applied tip bias, we are able to reversibly control and optimize the SMM contrast to image variations in electronic structure and the localized effects of surface contaminants. By further performing tip bias-dependent point spectroscopy together with finite element simulations, we distinguish the effects of the quantum capacitance and determine the local dominant charge carrier species and dopant concentration. These results underscore the capability of SMM for the study of 2D materials to image, identify, and study electronic defects.

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