Fig. 1: Defective PtSe2 crystal.
From: Disorder-induced bulk photovoltaic effect in a centrosymmetric van der Waals material
a, b The unit cell (a) and top and side view of 1T-phase PtSe2 crystal structure (b). c Raman spectra of monolayer PtSe2 samples produced by regular exfoliation (black line) and Au-assisted exfoliation (red line). Dotted black lines indicate characteristic Raman peaks from the regular regular exfoliated sample that are related to Eg, A1g, and LO phonon modes of 1T-phase PtSe2. Raman intensity from the Au-assisted exfoliation sample is multiplied by a factor of 10 for comparison. d STEM-HAADF image of a bilayer PtSe2 from Au-assisted exfoliation. The cluster-like defects are highlighted by orange dashed circles. The scale bar is 2 nm. e STEM-HAADF image with a small field of view. The green and gray dots represent Se and Pt atoms, respectively, and Se vacancies, displayed as dotted yellow circles, are visible. The scale bar is 5 Å.
