Effect of Strain on Second Harmonic Generation from Indium Selenide Few-Layers

Zi-Yi Li^1,2*, Hao-Yu Cheng¹, Hsuan-Chun Yao¹, Sheng-Hsun Kung¹, Christy Roshini Paul Inbaraj², Raman Sankar¹, Min-Nan Ou¹, Yang-Fang Chen², Chi-Cheng Lee³, Kung-Hsuan Lin¹

¹Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
²Department of Physics, National Taiwan University, Taipei 10617, Taiwan
³Department of Physics, Tamkang University, Tamsui, New Taipei 25137, Taiwan

* Presenter:Zi-Yi Li, email:a12859@hotmail.com

Few-layer InSe is an emerging 2D material, which exhibits potential to be excellent electronic and optoelectronic devices. For the applications of flexible devices, how strain (deformation) could alter the electronic and optical properties is thus an important issue. And second harmonic generation (SHG) is one of prominent tools to probe the structure of material. In this work, we studied angular-resolved SHG pattern of Indium Selenide (InSe) few-layers under strain both experimentally and theoretically. We used the exfoliation method to fabricate InSe 2D flake and measured its SHG signal while it was compressed. We found the SHG signal of InSe decreased while the compressive strain level increased. In addition, we calculated the second-order susceptibility of InSe under different strain, which qualitatively agreeing well with the experimental results. Photoelastic constants for SHG were retrieved, which could be used to map strain distribution of InSe with SHG images.

Keywords: Second Harmonic Generation, Strain, 2D Material, Indium Selenide