1. Engineering Optical and Electronic Properties of WS2 by Varying the Number of Layers
- Author
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Hyun-Jong Chung, Doo Hua Choi, Sung Ho Jhang, Han Byeol Lee, Jun-Ho Lee, Hakseong Kim, Wi Hyoung Lee, Hyun-Cheol Kim, Hyeonsik Cheong, Sangwook Lee, Jae-Ung Lee, and Bae Ho Park
- Subjects
Materials science ,business.industry ,Band gap ,Oscillation ,Schottky barrier ,Tungsten disulfide ,General Engineering ,General Physics and Astronomy ,Nanotechnology ,chemistry.chemical_compound ,chemistry ,Extinction (optical mineralogy) ,Monolayer ,Optoelectronics ,General Materials Science ,business ,Refractive index ,Electronic properties - Abstract
The optical constants, bandgaps, and band alignments of mono-, bi-, and trilayer WS2 were experimentally measured, and an extraordinarily high dependency on the number of layers was revealed. The refractive indices and extinction coefficients were extracted from the optical-contrast oscillation for various thicknesses of SiO2 on a Si substrate. The bandgaps of the few-layer WS2 were both optically and electrically measured, indicating high exciton-binding energies. The Schottky-barrier heights (SBHs) with Au/Cr contact were also extracted, depending on the number of layers (1-28). From an engineering viewpoint, the bandgap can be modulated from 3.49 to 2.71 eV with additional layers. The SBH can also be reduced from 0.37 eV for a monolayer to 0.17 eV for 28 layers. The technique of engineering materials' properties by modulating the number of layers opens pathways uniquely adaptable to transition-metal dichalcogenides.
- Published
- 2015