Growth of MoO 3 Films by RF Magnetron Sputtering: Studies on the Structural, Optical, and Electrochromic Properties

Abstract

Molybdenum oxide (MoO 3 ) 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 MoO 3 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 MoO 3 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 MoO 3 . 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 MoO 3 films formed on ITO coated glass substrates was studied and achieved the optical modulation of about 13% with color efficiency of about 20 cm 2 /C.