Effect of substrates on the growth of α-MoO3 nanostructures via plasma assisted sublimation process

In this communication, we have investigated the substrate effect on the growth of MoO3 nanostructured thin films prepared by plasma assisted sublimation process (PASP). Three different substrates viz. ITO glass, Ni/Si [100], and Ni/glass are used in deposition process. The surface analysis endorsed that Ni/Si and Ni/glass substrates are most favorable for the uniform growth of vertically aligned MoO3 nanoplates (NPs) and nanoflakes (NFs) of well controlled features with very high aspect ratio (height/thickness) >30, whereas nanostructure formed on ITO/glass substrate is improper (in terms of features and alignment). The X-ray diffractograms divulge that MoO3 films deposited on all substrates exhibit pure orthorhombic phase with preferential crystallographic orientation along [110] direction particularly in case of Ni/Si and Ni/glass substrates. Atomic force microscopic analysis reveals that the average substrates roughness enhanced in presence of pre-deposited layer and monitor the growth of nanostructures. High resolution transmission electron microscopic analysis with selected area diffraction pattern confirmed that both the MoO3 NPs and NFs are single crystalline in nature. The Raman and IR spectrum of all films further endorse the presence of single orthorhombic phase in accordance with the XRD results and also confirm the effect of nanosize on the vibrational properties.