Growth of molybdenum oxide (α-MoO3) layers through proximity evaporation: studying electronic properties and photo-responsivity

In this study, we successfully synthesized α-MoO₃ nanolayers using a proximity evaporation technique, positioning the Mo film approximately 1 mm from the target substrate at atmospheric conditions. This novel method bypasses the need for supplemental oxygen sources by utilizing ambient oxygen, resulting in cost-effective and scalable production of MoO₃. The α-MoO₃ films synthesized at an optimal growth temperature of 550 °C demonstrate well-controlled layer thickness, high crystallinity, and uniform stoichiometry. Detailed characterizations were performed, including XRD for crystallographic confirmation, SEM–EDS for morphology and stoichiometry, Raman spectroscopy for vibrational modes, and UV–Vis for optical properties, revealing a tunable bandgap of approximately 3.7 eV. I-V measurements indicated a high resistance of 8.7 × 10⁶ Ω, confirming the material’s insulating nature, and an optimum dielectric constant of 1253. Photo-response measurements demonstrated a significant photocurrent increase under illumination, with responsivity 8.8 A.W⁻¹, detectivity1.2 × 10¹³ J, and quantum efficiency of 18.5%, respectively. The proposed proximity evaporation technique demonstrates potential as a scalable approach for synthesizing high-quality two-dimensional (2D) transition metal oxides like MoO₃, with implications for applications in optoelectronics and sensing.