Fig. 1: Growth and characterization of physical vapor deposition (PVD) grown layered MoO3.
From: Controllable growth of MoO3 dielectrics with sub-1 nm equivalent oxide thickness for 2D electronics
a Scanning electron microscopy (SEM) image of vertically standing MoO3 nanoflakes grown on silicon substrates at 740 °C. b SEM image of MoO3 nanoflakes grown on silicon substrates at 790 °C. c Schematic of the polymer-free transfer method for transferring vertically grown MoO3 on target substrate. d Optical microscopy (OM) images of layered MoO3 with varying thicknesses on SiO2/Si substrates grown at different temperatures. e Atomic force microscopy (AFM) image showing the uniform thickness and clean surface of the as-grown MoO3 nanoflakes. f Raman spectra of MoO3 with varying thicknesses, three vertical dashed lines indicate the dominant Raman peaks at 666 cm−1, 817 cm−1 and 995 cm−1. g Ultraviolet–visible (UV–vis) absorption spectra of MoO3 with the corresponding plots of the Kubelka–Munk function, where λ, α, h and ʋ are wavelength, absorption coefficient, Planck’s constant and frequency of the incident light. Inset: the calculation of band gap, dashed line indicates Tauc’s equation result. h X-ray diffraction (XRD) pattern of the synthesized MoO3. i X-ray photoelectron spectroscopy (XPS) spectra of Mo 3 d core level.
