Thermal diffusivity downscaling of molybdenum oxide thin film through annealing temperature-induced nano-lamelle formation: a photothermal beam deflection study

Abstract

The present work proposes a method of downscaling the thermal diffusivity (α) of MoO3 thin films through annealing temperature-induced nano-lamelle formation. The thermal diffusivity modification of the MoO3 films, prepared by the doctor blade method, is investigated by the sensitive transverse photothermal beam deflection technique. The X-ray diffraction analysis confirms the structural phase transformation from monoclinic to orthorhombic in the films annealed from 300 to 450 °C. The thermal induced anisotropy of the film is evident from the variation of the morphology index and texture coefficient. The field emission scanning electron microscopic analysis unveils the morphology modifications from blocks to the nano-lamelle structure with layers of average thickness ~ 77 nm. The thermal diffusivity measurement reveals a 53% reduction upon annealing the film to 450 °C. The drastic reduction is achieved through the annealing temperature-induced nano-lamelle formation and the phase transformation from monoclinic to orthorhombic in the MoO3 films.