MOCVD of KNbO3 Ferroelectric Films and their Characterization

KNbO3 in the form of films is a highly acclaimed material due to its potential application in surface acoustic wave (SAW), and nonlinear optic devices. Single‐source powder flash evaporation MOCVD of epitaxial KNbO3 films was accomplished, for the first time, with potassium tert‐butoxide and niobium heteroligand complex, Nb(OiPr)4(thd) used as volatile metal–organic precursors. The microstructure of the films was found to be dependent on the substrate used (MgO or SrTiO3) and deposition temperature. A new approach to reach cation stoichiometry of deposited films deficient in potassium, consisting of a post‐deposition annealing with a KNbO3/K3NbO4 powder mixture, was proposed. The device quality of the films was verified by high second harmonic generation (SHG) output. The effect of the oxygen non‐stoichiometry of films on the phase transition temperature was proven. Epitaxial KNbO3 is deposited using single source powder flash evaporation MOCVD from potassium tert‐butoxide and Nb(O‐i‐Pr)4(thd) on two substrates, MgO and StTiO3 (Figure). The microstructure of the film is found to be dependent on the substrate the film is deposited on and on deposition temperature. Device quality of the films is verified by high second harmonic generation output. The effect of the oxygen non‐stoichiometry of the films on the phase transition temperatures is proven.