Effects of high temperature annealing on MOCVD grown CaCu3Ti4O12 films on LaAlO3 substrates

Calcium copper titanate, CaCu3Ti4O12 (CCTO), thin films have been fabricated by Metal Organic Chemical Vapor Deposition (MOCVD) on LaAlO3(100) single crystal substrates. Depositions have been carried out from a molten mixture consisting of the Ca(hfa)2•tetraglyme, Ti(tmhd)2(O-iPr)2, and Cu(tmhd)2 [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione; O-iPr = iso-propoxide] precursors. Post-deposition annealing treatments have been performed at 1100 °C for long time (24 h) as well as by rapid thermal annealing (RTA) processes. Since structural and chemical properties of CCTO ceramics greatly affect the resulting dielectric properties, accurate structural, morphological and compositional characterizations of the annealed samples have been performed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX). Oriented films have been obtained after both long time annealings and RTA processes, while different morphologies have been observed: ∼ 600 nm wide rounded grains and very large (∼ 5 μm) squared grains, respectively.