Strain-induced Giant Second-harmonic Generation in Monolayered $2H$-MoX${}_2$ (X=S,Se,Te)

Abstract

Dynamic second-order nonlinear susceptibilities, ${\chi }^{(2)}(2\omega ,\omega ,\omega )\equiv {\chi }^{(2)}(\omega )$, are calculated here within a fully first-principles scheme for monolayered molybdenum dichalcogenides, $2H$-MoX${}_2$ (X=S,Se,Te). The absolute values of ${\chi }^{(2)}(\omega )$ across the three chalcogens critically depend on the band gap energies upon uniform strain, yielding the highest ${\chi }^{(2)}(0)\sim$ 140 pm/V for MoTe${}_2$ in the static limit. Under this uniform in-plane stress, $2H$-MoX${}_2$ can undergo direct-to-indirect transition of band gaps, which in turn substantially affects ${\chi }^{(2)}(\omega )$. The tunability of ${\chi }^{(2)}(\omega )$ by either compressive or tensile strain is demonstrated especially for two important experimental wavelengths, 1064 nm and 800 nm, where resonantly enhanced non-linear effects can be exploited: ${\chi }^{(2)}$ of MoSe${}_2$ and MoTe${}_2$ approach $\sim$800 pm/V with -2\% strain at 1064 nm.

4 pages 4 figures,submitted to Phys. Rev. B, Accepted for Appl. Phys. Lett

References in corpus (3)

• The electronic properties of graphene
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States

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