Optical properties of large-area ultrathin MoS{sub 2} films: Evolution from a single layer to multilayers

Journal Article · Fri Nov 14 04:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4901464· OSTI ID:22402621

Park, Jun Woo; So, Hyeon Seob; Kim, Sung; Choi, Suk-Ho; Lee, Hosun ^[1]; Lee, Jinhwan; Lee, Changgu ^[2]; Kim, Youngchan ^[3]

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1. Department of Applied Physics, Kyung Hee University, Yong-In 446-701 (Korea, Republic of)
2. School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)
3. SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

We investigated the optical properties of ultrathin MoS{sub 2} films (number of layers: N = 1, 2, 4, and 12) using Raman spectroscopy, photoluminescence (PL) spectroscopy, and spectroscopic ellipsometry. We estimated the layer thicknesses based on Raman spectra. We characterized the microstructural properties of a single-layer MoS{sub 2} film using atomic force microscopy. We measured the lowest-energy A and B excitons using PL spectroscopy. We measured the ellipsometric angles (Ψ and Δ) of MoS{sub 2} thin films using spectroscopic ellipsometry, and obtained the dielectric functions as the films' thickness changed from a single layer to multi-layers. We determined the films' optical gap energies from the absorption coefficients. Applying the standard critical point model to the second derivative of the dielectric function (d{sup 2}ε(E)/dE{sup 2}), we determined several critical point energies. The d{sup 2}ε(E)/dE{sup 2} spectra showed doublet peaks around 3 eV corresponding to the C and D transitions, as well as doublet peaks around 2 eV corresponding to the A and B transitions. These doublet structures at 3 eV are attributed to the transitions in the Brillouin zone between the Γ and K points.

• OSTI ID: 22402621
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 18 Vol. 116; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
ATOMIC FORCE MICROSCOPY
BRILLOUIN ZONES
DIELECTRIC MATERIALS
ELLIPSOMETRY
EV RANGE
LAYERS
MICROSTRUCTURE
MOLYBDENUM SULFIDES
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
RAMAN SPECTRA
RAMAN SPECTROSCOPY
THICKNESS
THIN FILMS