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The absorption spectra of single-layer GaSe and GaTe in the hexagonal phase feature exciton peaks with distinct polarization selectivity. We investigate these distinct features from first-principle calculations using the GW-BSE formalisms. We show that the brightness of the exciton absorption peaks is tunable with the polarization of the light. Due to the symmetry of the bands under z-axis mirror symmetry, the bound exciton states selectively couple to either in-plane or out-of-plane polarization of the light. In particular, for a p-polarized light absorption experiment, the absorption peaks of the s-like excitons emerge at large angle of incidence, while the overall absorbance reduces over the rest of the spectrum.
GeSe and SnSe monochalcogenide monolayers and bilayers undergo a two-dimensional phase transition from a rectangular unit cell to a square unit cell at a temperature $T_c$ well below the melting point. Its consequences on material properties are stud
We use a first-principles density functional theory approach to calculate the shift current and linear absorption of uniformly illuminated single-layer Ge and Sn monochalcogenides. We predict strong absorption in the visible spectrum and a large effe
Understanding carrier creation and evolution in materials initiated by pulsed optical excitation is central to developing ultrafast optoelectronics. We demonstrate herein that the dynamic response of a system can be drastically modified when its phys
We carried out micro-Raman spectroscopy of graphene layers over the temperature range from approximately 80 K to 370 K. The number of layers was independently confirmed by the quantum Hall measurements and atomic force microscopy. The measured values
We report measurements of the optical response of polycrystalline DyN thin films. The frequency-dependent complex refractive index in the near IR-visible-near UV was determined by fitting reflection/transmission spectra. In conjunction with resistivi