Predicting the Raman spectra of ferroelectric phases in two-dimensional Ga₂O₃ monolayer

We investigate the vibrational properties and Raman spectra of the two-dimensional Ga₂O₃ monolayer, using density functional theory. Two ferroelectric (FE) phases of the Ga₂O₃ monolayer with wurtzite (WZ) and zinc blende (ZB) structures (FE-WZ and FE-ZB, respectively) are considered. The Raman tensor and angle-dependent Raman intensities of two major Raman peaks (A11 and A21) in both FE-WZ (497, and 779 cm^-1) and FE-ZB (481, and 772 cm^-1) Ga₂O₃ monolayers, are calculated for the polarization of scattered light, parallel and perpendicular to that of the incident light. The characteristics of angle-dependent Raman intensities are analyzed. The average non-resonant Raman spectra of the minor peaks in FE-WZ (E¹) and FE-BZ (E¹ and E²) are compared with those of major peaks A11 and A21. These predictions of the Raman spectra of the Ga₂O₃ monolayer may guide the rational design of two-dimensional optical devices.