Substrate Surface Symmetric induced Strain Effect of 2D-GaSe Grown by Molecular Beam Epitaxy

Cheng-Wei Liu^1*, Jin‑Ji Dai¹, Ssu‑Kuan Wu¹, Nhu‑Quynh Diep¹, Sa‑Hoang Huynh¹, Hua‑Chiang Wen¹, Wu‑Ching Chou¹, Ji‑Lin Shen², Chi‑Tsu Yuan²

¹電子物理, 國立交通大學, 新竹市, Taiwan
²物理系, 中原大學, 中壢市, Taiwan

* Presenter:Cheng-Wei Liu, email:william798424@gmail.com

Two-dimensional (2D) layered GaSe films were grown on GaAs (001), GaN/Sapphire, and Mica substrates by molecular beam epitaxy. The in-plane orientations of nucleated GaSe layers grown on hexagonal GaN/Sapphire and Mica substrates are revealed randomly, whereas single-orientation GaSe domain is predominant in the GaSe/GaAs (001) sample monitoring by in-situ reflective high-energy electron diffraction (RHEED). The unintentionally biaxial in-plane tensile strains are observed in all samples and investigated by photoluminescence spectra and Raman scattering, significant red-shift in bound exciton emissions, and the frequency of in-plane E_2g^2vibration modes. The dissimilarity of symmetrical surface structure between the 2D-GaSe layers and the substrates during the epitaxial growth process induced strain effect. The lattice parameters and strain behavior of these samples can be fully obtained from RHEED, XRD, and Raman scattering measurements. The results in this study pave the way in strain engineering and optical manipulation of 2D layered GaSe materials for novel electronic and optoelectronic device applications in the future.

Keywords: Molecular Beam Epitaxy, Two-dimensional GaSe, Strain effect