Cyclic Chemical Vapor Deposition of Nickel Ferrite Thin Films Using Organometallic Precursor Combination

Abstract

This work introduces the fabrication of nano scale magnetostrictive NiFe2O4 (NFO) thin films using reduced pressure metallorganic chemical vapor deposition (MOCVD) with programmable cyclic pulsing of novel precursor combination — n-butylferrocene and nickelocene. Using a custom-designed CVD system, different rate-limiting steps and Ea in the CVD of iron oxide and nickel oxide depositions are discussed. Both cyclic-deposition and co-deposition modes were investigated through NFO depositions on silicon substrates at 17 Torr and 500°C. Growth rates of NFO films obtained by co-deposition and cyclic-deposition were 3 and 1.6 nm/min, respectively. Material characterizations were conducted on NFO films fabricated at optimized process conditions and annealed samples. Rutherford backscattering spectroscopic results showed better stoichiometric control for cyclic-deposited films. As-deposited NFO films showed homogeneous stoichiometric chemical composition without carbon contamination in the bulk film; a saturation magnetization of 25 emu/g was observed from its trevorite crystalline phase upon annealing at 700°C in argon ambience for one hour.