Fig. 2: Optical characterizations of InSe and InSe:Y.
From: Sliding ferroelectricity in van der Waals layered γ-InSe semiconductor
a Transmission spectra at room temperature. The inset gives the corresponding Tauc-plots. b Reflectance spectra at room temperature. c TR-PL images with peaks PA and PB of InSe (upper) and InSe:Y (lower) at 4 K. d Transient-PL curves at t < 0 ps (i.e., before the next pulse). e PL decay curves at ~1240 meV and 1300 meV for both samples. The inset gives the corresponding lifetimes from the fit procedure with a single-exponential decay function. The calculated band structure of InSe (f) and the energy eigenvalues for selected k-points near valence band maximum (VBM) based on the supercell of InSe (g) and InSe:Y (h) (Methods, Supplementary Fig. 5). The bandgap widens with Y-doping, and the VBM stays at the A point. No defect level is introduced in the bandgap by Y-doping.
