Investigations on morphological and electrical studies of sputtered MoO₃ films

Molybdenum oxide (MoO₃) films were deposited by sputtering of molybdenum target under different substrate temperatures 303–673 K using DC magnetron sputtering. Sputtered MoO₃ films under optimized conditions show nano structured grains whose size is around 140 nm, while roughness of the films will increase from 5.7 to 70 nm due to grain growth and mechanical stress development on the films. The microhardness of MoO₃ films increased from 0.49 to 1.28 GPa with increase of substrate temperature. The electrical resistivity of the MoO₃ films at 303 K is 0.27 × 10⁴ Ω cm increases to 1.9 × 10⁴ Ω cm with increase of substrate temperature and then decreases at higher substrate temperature. The activation energies of the films at higher temperature region was varied from 0.98 to 1.30 eV while at low temperature region the activation energies were in the range 0.02–0.10 eV. The refractive index of MoO₃ films increases from 2.03 to 2.18 with increase of substrate temperature from 303 to 673 K due to packing density. The change in morphological and microhardness properties can be explained due to the existence of a mixed phases and stoichiometric films.