Tuning the optoelectronic properties of amorphous MoOx films by reactive sputtering

In this letter, we report on the effect of oxygen partial pressure and sputtering power on amorphous DC-sputtered MoOx films. We observe abrupt changes in the optoelectronic properties of the reported films by increasing the oxygen partial pressure from 1.00 x 10(-3) mbar to 1.37 x 10(-3) mbar during the sputtering process. A strong impact on the electrical conductivity, varying from 1.6 x 10(-5) S/cm to 3.22 S/cm, and on the absorption coefficient in the range of 0.6-3.0 eV is observed for the nearly stoichiometric MoO3.00 and for the sub-stoichiometric MoO2.57 films, respectively, without modifying significantly the microstructure of the studied films. The presence of states within the band gap due to the lack of oxygen is the most probable mechanism for generating a change in electrical conductivity as well as optical absorption in DC-sputtered MoOx. The large tuning range of the optoelectronic properties in these films holds strong promise for their implementation in optoelectronic devices. (C) 2015 AIP Publishing LLC.