Plasma-Assisted MOCVD of Titanium Oxide and its Composite Coatings Using Metallo-organic Precursors

Titanium oxide (TiO2) films and composite coatings with nickel were synthesized by plasma‐assisted, metal‐organic (PAMO) CVD using the MO complexes bis(2‐N‐(2‐hydroxy‐2‐methylethylimino)‐4‐pentanoate)titanium(IV) and N,N′‐ethylene‐bis(2,4‐pentanedion‐iminoato)nickel(II). The growth of such films was investigated in various plasma environments (Ar or N2) in the substrate temperature range 450–550 °C under a deposition pressure of 1–2 mbar. The phase identification using grazing incidence X‐ray diffraction (GIXRD) showed TiO2 crystallized in anatase form, while that of nickel in composite films was found to be a face centered cubic (fcc) structure. The surface morphology analysis using scanning electron microscopy (SEM) revealed a grainy and sponge‐like structure for TiO2 films, whereas smooth and densely packed agglomerates could be observed for Ni/TiO2 composite films. Chemical analysis by energy dispersive X‐ray (EDX) analysis showed the presence of titanium, nickel, and oxygen in the films. X‐ray photoelectron spectroscopy (XPS) confirmed the chemical state of the elements in the deposited composite films to be Ti+4 and Ni0. Prior to the deposition of TiO2 and its composite films, the Ti precursor was subjected to equilibrium vapor pressure measurements by employing thermogravimetric/differential thermal analysis (TG/DTA) in transpiration mode, which led to the value of 46.25 ± 2.7 kJ mol–1 for the standard enthalpy of sublimation (ΔH°sub). A plasma‐assisted MOCVD technique is adapted for the deposition of anatase TiO2 and its composite coatings with Ni using solid metallo‐organic precursors. GIXRD of the deposited films over Si substrates confirms the crystalline nature of TiO2 and Ni/TiO2 films. XPS analysis of the as‐deposited and sputtered samples reveals the bi‐phasic structure of composite films as well as ascertaining their chemical states. The films are analyzed by SEM/EDX for their microstructure and composition.