Development of hierarchical layered nanostructured α-MoO3 thin films using dc magnetron sputtering

Abstract

The synthesis of environmentally friendly, catalyst free, hierarchical molybdenum oxide nanostructured thin films of different morphologies by a DC magnetron sputtering technique is reported. With increase in the annealing temperature, the spherical molybdenum nanoparticles arrange themselves in the form of vertically aligned nanorods and platelets stacked over one another. The preliminary phase analysis was carried out using x-ray diffraction. The sample annealed at 600 °C shows the formation of highly crystalline orthorhombic α-MoO3. Field emission scanning electron microscopy and transmission electron microscopy images confirm the formation of a layered structure at higher annealing temperatures, while the Raman spectroscopy revealed the stretching vibration modes of Mo–O bonds in the formation of the orthorhombic α-MoO3 layered structure. The Raman peaks at 667, 820 and 995 cm−1 correspond to the layered structure of orthorhombic α-MoO3. The electrical properties and possible growth mechanism of the as-prepared samples at different annealing temperatures are also discussed.