  Doping is an effective way to tune the property of metal oxides1-5, for
achieving functional oxide electronics6-8. Previously we developed a
controllable hydrogen doping technology at ambient conditions by use of
electron-proton synergistic doping strategy, which enables one to get rid of
high-temperature/pressure treatments required by traditional technologies9.
Here, based on this facile doping route, we achieve a visual and reversible
insulator-metal transition (MIT) for tungsten trioxide (WO3) film. Its
outstanding spatial selection is comparable to standard UV lithography, which
shows the potential of becoming a viable way for rewritable WO3 grating device
fabrication. Furthermore, the period of the obtained WO3 structural grating can
also be easily changed for requirement by doping area selection. This advanced
doping technology opens up alternative approaches for developing not only
optical devices, but also rewritable ions devices and integrated circuits for
various oxide electronics.
