Optical characterization of molybdenum oxide thin films deposited by chemical vapor transport of MoO3(OH)2

Abstract

MoO3 thin films have been extensively investigatedin the electrochromic (EC) device field due to its superior optical properties; electrochromism is simply defined as a color change caused by an applied bias. Recently, many deposition techniques to deposit Mo oxide thin films have been developed including chemical vapor deposition (CVD), evaporation, sol-gel coating, RF magnetron sputtering, and pulsed laser deposition (PLD). In this study, MoO2 thin films was homogeneously deposited by the chemical vapor transport (CVT) of MoO3(OH)2 during reduction of MoO3 powder in H2. Subsequently, a MoO3 thin film was obtained by annealing of the deposited MoO2 at 400oC for various holding times in O2. As annealing commenced, the optical transmittance of the films increased due to the crystallinity resulting from phase change and subsequent reduced oxygen vacancy and it was discussed through the changes of the optical bandgap energy.