Structural, optical and electrochromic properties of sputter deposited tungsten oxide films in argon-helium atmosphere

Abstract

Tungsten oxide (WO3) films have been deposited on glass substrates by radio frequency magnetron sputtering of tungsten target. We examined the effect of oxygen flow rate in argon and helium atmosphere on the structural, optical, and electrochromic properties of WO3 films. When helium gas is replaced with argon, the particle sizes and the band gap will get affected. Band gap values were obtained over a range of 2.62 eV to 3.09 eV. The atomic mass of the sputtering gas also plays a prime role in changing the primary crystallite size, orientation, as well as band gap. We could relate the crystallization of tungsten atoms with low oxygen flow rate when films are deposited in helium instead of argon due to Penning ionization.