2023, Observation of Optical Anisotropy and Linear Dichroism Transition in Layered Silicon Phosphide, Nanoscale

2023, Observation of Optical Anisotropy and Linear Dichroism Transition in Layered Silicon Phosphide, Nanoscale

Abstract:

The investigation of in-plane two-dimensional (2D) anisotropic materials has garnered significant attention due to their exceptional electronic, optical, and mechanical characteristics. The anisotropic optical properties and angle-dependent photodetectors of 2D anisotropic materials have been extensively studied. However, the novel in-plane anisotropic materials still need to be explored to satisfy for distinct environment and devices. Here, we report the remarkable anisotropic behavior of excitons and demonstrate a unique linear-dichroism transition of absorption between ultraviolet and visible light in layered SiP through the analysis of polarization PL and absorbance spectra. Its high absorption linear-dichroism ratio of 1.16 at 388 nm, 1.15 at 532 nm, and 1.19 at 733 nm is revealed, suggesting the brilliant non-isotropic responses. The robust periodic variation of the A1 and A2 Raman modes in 2D SiP materials allows for the determination of their crystal orientation. Furthermore, the presence of indirect excitons with phonon sideband in the temperature-dependent PL spectra exhibit non-monotonic energy shifts with increasing temperature, which is attributed to enhanced electron-phonon interaction and thermal expansion. Our findings provide valuable insights into the fundamental physical properties of layered SiP and offer guidelines for designing polarization-sensitive photodetectors and angle-dependent devices based on 2D anisotropic materials.

Keywords: anisotropic materials , Linear Dichroism Transition, SiP materials, electron-phonon interaction 

Link: https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr01765f/unauth

Observation of optical anisotropy and a linear dichroism transition in layered silicon phosphide.pdf