Atomic layer deposition of crystalline molybdenum trioxide and suboxide thin films using molybdenum(II) acetate dimer precursor

Molybdenum oxide thin films are of interest due to a large range of possible phases, high work functions, and catalytic activity. These films have applications in areas, such as sensors, chromic, and semiconductor devices. In this work, a molybdenum(II) acetate dimer precursor was used with ozone for the atomic layer deposition of molybdenum oxide thin films. The films were grown at 200–300 °C yielding highly crystalline films even at the lowest deposition temperatures. X-ray diffraction measurements showed that the as-deposited films consist of molybdenum suboxides and/or a phase-pure orthorhombic molybdenum trioxide phase depending on the deposition conditions. Time-of-flight elastic recoil detection analysis showed that the stoichiometry was close to molybdenum trioxide, and the films were exceptionally pure with main impurities being hydrogen and carbon, which were at the detection limit of the instrument (0.1 at. %). This process, allowing the deposition of very pure and highly crystalline thin films with tunable phases and oxidation states, is very promising for future industrial applications.