Monolayer tungsten diselenide (1H-WSe?) flakes have been exfoliated from bulk tungsten diselenide (2H-WSe?) onto 90nm thermal oxide and measures from 5micron up to 40micron in size. Each sample contains at least one single-layer WSe? and is easy to find with the given x and y coordinates. Full characterization is performed on each monolayer flake. Typically, single-layer WSe? show strong PL at 1.66eV with 0.04 to 0.08eV FWHM, and the Raman peaks are located at 139.5cm-1 (E2g in-plane mode) and 249.5 cm-1 (A1g out-of-plane mode). All the data is provided with the sample and data includes Raman, photoluminescence, 100x optical images, and x,y coordinates.

Characterization

Raman spectroscopy: Raman spectroscopy is data is taken on every single-layer flakes. Typically, flakes show two prominent Raman peaks at 139.5cm-1 (E2g- in plane-) and 249.5cm-1 (A1g out-of-plane) and the FWHM (full-width-at-half-maximum) is less than 5cm-1. Photoluminescence (PL): In the single layer form, tungsten diselenide possesses direct band-gap at 1.65eV. PL measurements show strong PL peak located at 1.66eV with 0.04-0.08 eV PL FWHM.

Optical Microscope images: Each sample is inspected under the optical microscope and x-y coordinates are recorded.

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Possible applications:

Electronics
Sensors - detectors
Optics
STM - AFM applications
Molecular detection - binding
Ultra-low friction studies
Materials science and semiconductor research