Evolution of electronic structure in atomically thin sheets of WS2 and WSe2.

By Weijie Zhao, Z. Ghorannevis, L. Chu, M. Toh, Christian Kloc, P. Tan, G. Eda. ACS Nano, 2012

1,985 citations recorded by the source corpus.

Geometrical confinement effect in exfoliated sheets of layered materials leads to significant evolution of energy dispersion in mono- to few-layer thickness regime. Molybdenum disulfide (MoS(2)) was recently found to exhibit indirect-to-direct gap transition when the thickness is reduced to a single monolayer. Emerging photoluminescence (PL) from monolayer MoS(2) opens up opportunities for a range of novel optoelectronic applications of the material. Here we report differential reflectance and PL spectra of mono- to few-layer WS(2) and WSe(2) that indicate that the band structure of these materials undergoes similar indirect-to-direct gap transition when thinned to a single monolayer. The transition is evidenced by distinctly enhanced PL peak centered at 630 and 750 nm in monolayer WS(2) and WSe(2), respectively. Few-layer flakes are found to exhibit comparatively strong indirect gap emission along with direct gap hot electron emission, suggesting high quality of synthetic crystals prepared by a chemical vapor transport method. Fine absorption and emission features and their thickness dependence suggest a strong effect of Se p-orbitals on the d electron band structure as well as interlayer coupling in WSe(2).

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/eac9858b0374e34f8280ea7425827bf74c353289

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Electrical and Electronic Engineering

1. A. Castellanos-Gómez
2. Dmitri Golberg
3. Xiaodong Xu
4. Yoshio Bando
5. W. Yao
6. Andras Kis
7. D. Mandrus
8. G. Burkard

In Materials Chemistry

1. A. Castellanos-Gómez
2. W. Yao
3. Xiaodong Xu
4. Fengnian Xia
5. Dmitri Golberg
6. Li Yang
7. P. Tan
8. Yoshio Bando

Citations in the corpus

• Environmental instability of few-layer black phosphorus (2014, neutral): “[16] Weijie Zhao, Zohreh Ghorannevis, Leiqiang Chu, Minglin Toh, Christian Kloc, Ping-Heng Tan,”
• Wafer-scale synthesis of monolayer WS2 for high-performance flexible photodetectors by enhanced chemical vapor deposition (2018, background): “The separation between the A and B peaks is attributed to the splitting of the valence band minimum due to the spin-orbit coupling at the K (K’) valley [41].”