Characterization of MoO₃ and Ti_xMo_yO_z Thin Films Prepared by Atomic Layer Deposition

This work involves the ex situ characterization of molybdenum oxide (MoO₃) and titanium molybdenum oxide (Ti_xMo_yO_z) thin films grown by atomic layer deposition (ALD) at 150°C using titanium tetrachloride (TiCl₄), molybdenum oxytetrachloride (MoOCl₄), and water. Atomic layer deposition of Ti_xMo_yO_z was carried out in supercycles consisting of TiCl₄/H₂O and MoOCl₄/H₂O subcycles. Two types of Ti_xMo_yO_z films were prepared, where the ratio of subcycles was 1 : 1 (1Ti1MoO) and 1 : 7 (1Ti7MoO). The film growth rate was determined by spectroscopic ellipsometry (SE) and X-ray reflectivity (XRR). The density and root-mean-square roughness of the films were also determined from XRR. The composition of the films was determined by X-ray photoelectron spectroscopy (XPS). The degree of oxidation of molybdenum in the MoO₃ and 1Ti7MoO films was +6, and in the 1Ti1MoO film, molybdenum was found in the oxidation states of +5 and +6. X-Ray diffraction analysis (XRD) showed that the films were amorphous.