Growth of centimeter-scale single crystal MoO₃ ribbons for high performance ultraviolet photodetectors

Molybdenum oxides have attracted much interest due to their unique electronic properties. Here, we report a convenient and efficient method to synthesize centimeter-scale single crystal of MoO₃ ribbons through an atmospheric pressure physical vapor deposition approach. Optical microscopy, atomic force microscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction, and x-ray diffraction measurements reveal that the MoO₃ ribbons grow along the MoO₃⟨100⟩ direction and the top surface is MoO₃(010) plane. Raman spectroscopy, x-ray photoelectron spectroscopy, and cross-sectional HRTEM results disclose that the surface of MoO₃ ribbons can be transformed from MoO₃ to MoO₂ through H₂ annealing treatment forming MoO₂/MoO₃ heterostructure. We found that the conductance and ultraviolet photoresponsivity of the MoO₃ ribbons can be improved by ∼11 and ∼5 orders of magnitude, respectively, after H₂ annealing treatment, which will be helpful for the applications of MoO₃ in the optoelectronic field. © 2021 Author(s).