Ultraviolet and Visible State of the Molybdenum Oxide MoO3 thin Films Synthesized by Spray Pyrolysis Technique

Ultraviolet and Visible transmission measurements are performed over a wavelength range 190-2500 nm on the MoO3 thin films synthesized by spray pyrolysis technique at different substrate temperature and 3 min. spray time. The appeared bands are fitted and deconvaluted by Lorentz model. The higher energy band corresponds to the transition from valance band to conduction band while the lower energy band corresponds to the transition between oxidation states of molybdenum. Two sub-bands are resolved which are affected by substrate temperature and corresponds the electron transition between the molybdenum oxidation states Mo⁴⁺, Mo⁵⁺ and Mo⁶⁺. The transition from Mo5+ to Mo6+ oxidation states show a blue shift up to Tc =325^◦C. Above Tc, the transition Mo⁵⁺ to Mo⁶⁺ increases more drastically, resulting in an anomaly in the temperature-induced shift at Tc. The anomaly can be attributed to the amorphous-to-crystalline phase transition at 325◦C. Also, both refractive index and extinction coefficient are calculated as a function of substrate temperature.