Effect of the Substrate Temperature on the Structural and Morphological Properties of MoO2 Thin Films Obtained by Pulsed Injection MOCVD

Molybdenum oxides is of great technological interest due to their outstanding optical, electronic and catalytic properties. In this work, molybdenum dioxide (MoO2) thin films were deposited onto Si wafers and stainless steel substrates at different substrate temperatures. The growth of the films was achieved by using a vertical metal organic chemical vapor deposition reactor working in pulsed injection mode. A powder of molybdenum hexacarbonyl mixed in a toluene solution was used as precursor. An effective pulsed injection system to supply the precursor, usually used for fuel injection in internal combustion devices, delivers a precise amount of liquid precursor to the reactor through injectors, whose pulse intervals (injection frequency) are controlled by a computer-driven system. The use of a liquid solution as precursor along with the experimental parameters provide thermodynamically favorable conditions to fabricate a thin solid film, homogenously deposited onto the whole substrate. The MoO2 film structure and morphology were studied by X-ray diffraction, Raman scattering spectroscopy and scanning electron microscopy. Moreover, a comparative study was undertaken whereby the catalytic activity of stainless steel substrate for hydrogen evolution reaction was related to that of MoO2 thin film.