MoO3 films were deposited on Corning glass and silicon substrates held at room temperature (303 K) by RF magnetron sputtering of metallic molybdenum target at a fixed oxygen partial pressure of 4x10 -4 mbar and sputter pressure of 4x10 -2 mbar. The as deposited films were annealed in air at different temperatures in the range 473 -673 K. X-ray diffraction studies suggest that the as-deposited and the films annealed at 473 K were amorphous in nature, while those annealed at 573 and 673 K were polycrystalline with mixed phases of αorthorhombic and βmonoclinic MoO3. Scanning electron microscope images of the films annealed at 573 and 673 K exhibited nanoflower like and nanodisk like structures due to improvement in the crystallinity. Fourier transform infrared studies showed the characteristic vibrations of MoO3 with shift in the vibrational modes of Mo = O and Mo -O -Mo with increase of annealing temperature. The optical absorption edge of the films shifted towards lower wavelengths side with increase of annealing temperature. Optical band gap of as-deposited films was 2.98 eV with refractive index 2.01, while those annealed at 673 K showed the optical band gap of 3.15 eV and refractive index of 2.08. The MoO3 films annealed at 673 K were of nanocrystalline with crystallite size of 39 nm with optical band gap of 3.15 eV and refractive index of 2.08 were favorable for electron blocking and hole-selective layers in bulk-heterojuction solar cells.

Molybdenum oxide (MoO3) films were deposited on glass and silicon substrates held at temperature 473 K by RF magnetron sputtering of molybdenum target at various oxygen partial pressures in the range 8×10-5–8×10-4 mbar. The deposited MoO3 films were characterized for their chemical composition, crystallographic structure, surface morphology, chemical binding configuration, and optical properties. The films formed at oxygen partial pressure of 4×10-4 mbar were nearly stoichiometric and nanocrystalline MoO3 with crystallite size of 27 nm. The Fourier transform infrared spectrum of the films formed at 4×10-4 mbar exhibited the characteristics vibrational bands of MoO3. The optical band gap of the films increased from 3.11 to 3.28 eV, and the refractive index increased from 2.04 to 2.16 with the increase of oxygen partial pressure from 8×10-5 to 8×10-4 mbar, respectively. The electrochromic performance of MoO3 films formed on ITO coated glass substrates was studied and achieved the optical modulation of about 13% with color efficiency of about 20 cm2/C.

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MoO3 films were deposited by RF magnetron sputtering technique on glass and silicon substrates held at 473 K by sputtering of metallic molybdenum target at an oxygen partial pressure of 4 × 10−2 Pa and at different sputtering pressures in the range of 2 Pa to 6 Pa. The influence of sputtering pressure on the structure and surface morphology, electrical and optical properties of the MoO3 thin films was studied. X-ray diffraction studies suggest that the films deposited at a sputtering pressure of 2 Pa were polycrystalline in nature with mixed phase of α- and β-phase MoO3, while those formed at sputtering pressure of 4 Pa and above were of α-phase MoO3. Scanning electron micrographs showed a decrement in the size of the particles and their shapes changed from needle like structure to dense films with the increase of sputtering pressure. Fourier transform infrared spectroscopic studies confirmed the presence of characteristic vibration modes of Mo=O, Mo–O and Mo–O–Mo related to MoO3. Electrical resistivity of the MoO3 films decreased from 6.0 × 104 Ω cm to 2 × 104 Ω cm with an increase of sputtering pressure from 2 Pa to 6 Pa, respectively. Optical band gap of the films decreased from 3.12 eV to 2.86 eV with the increase of sputtering pressure from 2 Pa to 6 Pa, respectively.