Nonlinear Optical Responses of Janus MoSSe/MoS<sub>2</sub> Heterobilayers Optimized by Stacking Order and Strain
Nguyen Tuan Hung, Kunyan Zhang, Vuong Van Thanh, Yunfan Guo, Alexander A. Puretzky, David B. Geohegan, Jing Kong, Shengxi Huang, Riichiro Saito
Abstract
Nonlinear optical responses in second harmonic generation (SHG) of van der Waals heterobilayers, Janus MoSSe/MoS 2, are theoretically optimized as a function of strain and stacking order by adopting an exchange-correlation hybrid functional and a real-time approach in first-principles calculation. We find that the calculated nonlinear susceptibility, χ (2), in AA stacking (550 pm/V) becomes three times as large as AB stacking (170 pm/V) due to the broken inversion symmetry in the AA stacking. The present theoretical prediction is compared with the observed SHG spectra of Janus MoSSe/MoS 2 heterobilayers, in which the peak SHG intensity of AA stacking becomes four times as large as AB stacking. Furthermore, a relatively large, two-dimensional strain (4%) that breaks the C 3 v point group symmetry of the MoSSe/MoS 2, enhances calculated χ (2) values for both AA (900 pm/V) and AB (300 pm/V) stackings 1.6 times as large as that without strain.