English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

High quality WSe2 films have been grown on bilayer graphene (BLG) withlayer-by-layer control of thickness using molecular beam epitaxy (MBE). Thecombination of angle-resolved photoemission (ARPES), scanning tunnelingmicroscopy/spectroscopy (STM/STS), and optical absorption measurements revealthe atomic and electronic structures evolution and optical response ofWSe2/BLG. We observe that a bilayer of WSe2 is a direct bandgap semiconductor,when integrated in a BLG-based heterostructure, thus shifting thedirect-indirect band gap crossover to trilayer WSe2. In the monolayer limit,WSe2 shows a spin-splitting of 475 meV in the valence band at the K point, thelargest value observed among all the MX2 (M = Mo, W; X = S, Se) materials. Theexciton binding energy of monolayer-WSe2/BLG is found to be 0.21 eV, a valuethat is orders of magnitude larger than that of conventional 3D semiconductors,yet small as compared to other 2D transition metal dichalcogennides (TMDCs)semiconductors. Finally, our finding regarding the overall modification of theelectronic structure by an alkali metal surface electron doping opens a routeto further control the electronic properties of TMDCs.

Electronic Structure, Surface Doping, and Optical Response in Epitaxial WSe2 Thin Films