Microwave near-field imaging of two-dimensional semiconductors.

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.

DOI: 10.1021/nl504960u

Cite this paper

@article{Berweger2015MicrowaveNI, title={Microwave near-field imaging of two-dimensional semiconductors.}, author={Samuel Berweger and Joel C Weber and Jimmy John and Jesus M. Velazquez and Adam P Pieterick and Norman A Sanford and Albert Davydov and Bruce S Brunschwig and Nathan S. Lewis and Thomas M. Wallis and Pavel Kabos}, journal={Nano letters}, year={2015}, volume={15 2}, pages={1122-7} }