Details

Autor(en) / Beteiligte

• Janisch, Corey
• Wang, Yuanxi
• Ma, Ding
• Mehta, Nikhil
• Elías, Ana Laura
• Perea-López, Néstor
• Terrones, Mauricio
• Crespi, Vincent
• Liu, Zhiwen

Titel

Extraordinary Second Harmonic Generation in tungsten disulfide monolayers

Ist Teil von

• Scientific reports, 2014-07, Vol.4 (1), p.5530-5530, Article 5530

Ort / Verlag

England: Nature Publishing Group

Erscheinungsjahr

2014

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• We investigate Second Harmonic Generation (SHG) in monolayer WS₂ both deposited on a SiO₂/Si substrate or suspended using transmission electron microscopy grids. We find unusually large second order nonlinear susceptibility, with an estimated value of d(eff) ~ 4.5 nm/V nearly three orders of magnitude larger than other common nonlinear crystals. In order to quantitatively characterize the nonlinear susceptibility of two-dimensional (2D) materials, we have developed a formalism to model SHG based on the Green's function with a 2D nonlinear sheet source. In addition, polarized SHG is demonstrated as a useful method to probe the structural symmetry and crystal orientation of 2D materials. To understand the large second order nonlinear susceptibility of monolayer WS₂, density functional theory based calculation is performed. Our analysis suggests the origin of the large nonlinear susceptibility in resonance enhancement and a large joint density of states, and yields an estimate of the nonlinear susceptibility value d(eff) = 0.77 nm/V for monolayer WS₂, which shows good order-of-magnitude agreement with the experimental result.