Fig. 1: Structure, growth, and characterization of ultrathin Bi2SiO5 single crystals.
From: Vertically grown ultrathin Bi2SiO5 as high-κ single-crystalline gate dielectric
a Crystal structure of Bi2SiO5 (Cc, a = 15.12 Å, b = 5.44 Å, c = 5.29 Å, β = 90.07°) with alternatively stacked [Bi2O2]n2n+ and [SiO3]n2n− layers. b Calculated band structure and density of states (DOS) of Bi2SiO5 with a direct band gap of ~3.79 eV. The first Brillouin zone is inserted in the right panel. c Typical optical micrograph (OM) image of square Bi2SiO5 nanoplates showing an in-plane growth mode on mica substrate. d OM images of Bi2SiO5 nanoplates with thickness-dependent color contrasts on mica. The inset shows the typical atomic force microscope (AFM) image of an ultrathin Bi2SiO5 nanoplate with a thickness of 3.9 nm (5 layers) and an atomically smooth surface. e Scanning electron microscopy (SEM) image of 2D Bi2SiO5 crystals vertically grown on mica substrate. f Thickness-dependent color contrasts for Bi2SiO5 nanoplates transferred onto SiO2/Si substrate by a polymer-free mechanical pressing. The AFM image of a 7.5-nm-thick Bi2SiO5 nanoplate was inserted in f. g Typical AFM image of a terraced Bi2SiO5 nanoplates with a clear step of 0.76 nm. h, i Cross-sectional atomic-resolved high angle annular dark field (HAADF) images (left) and corresponding fast Fourier transform (FFT) diffraction spots (right) of chemical vapor deposition (CVD) grown Bi2SiO5 nanoplates taken along the zone axes of [010] (h) and [011] (i), respectively.
