Fig. 2: The characterizations and theoretical calculations for the electron doping WO3 film.
From: Spatially-resolved insulator-metal transition for rewritable optical gratings
a The secondary-ion mass spectrum (SIMS) tests for the WO3 film after treated by electron–proton synergistic doping route, labeled by HxWO3. Then the HxWO3 annealed at 300 °C in air leads to the restored WO3 sample. b The Raman peak at 802 cm−1 for pristine WO3 film is disappeared in HxWO3. While it can be restored after annealing the HxWO3 sample. c The UV–Vis–infrared transmission curves for the pristine WO3, the HxWO3 and the restored WO3 samples. d Resistance–temperature (R–T) results show the resistance of pristine WO3 film is quite stable within the temperature from 40 to 100 degrees, while it will decrease with six orders of magnitude after the film was hydrogenated to HxWO3, indicating a pronounced metal–insulator transition (MIT). The inset is the R–T cycle test in air, showing the metallic HxWO3 is quite stable at ambient. e Computed differential charge distribution at Zn/WO3 interface. Isosurface is 0.005 electrons per Å3. f Energy diagram along the reaction pathways of H migrating from WO3 surface (initial state: IS) to subsurface (final state: FS) via the transition state (TS). Energy of IS is set as zero. g, h Density of states (DOS) of WO3 (g) and H-doped WO3 (h), together with inset photographs for the atomic models.
