CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

However, using traditional vaporization methods (bubbler or crucible), accurate control of vapor
concentrations for the two components in order to obtain stoichiometric films is difficult, often
resulting in unwanted impurity phases such as Fe2O3 or NiO.[108] Precursor oligormerization
(e.g., [Ni(acac)2]3) and weak thermal stability above 200˚C are two additional drawbacks of this
approach.[109] To the best of our knowledge, no research has been reported for lithium ferrite
thin film deposition by using CVD technique with any metal organic precursors so far.
Fig. 18. Schematic diagram of a previous reported DLI-CVD system for nickel ferrite growth. Reproduced with
permission from ref. [83].
The direct liquid injection (DLI) technique, which can generate vapor from a liquid
solution source at relatively low temperatures (< 200°C), has in recent years been successfully
utilized for a number of metal-organic chemical vapor deposition processes.[110-112] DLI-CVD
is a particularly useful method for multi-component systems as several precursors can be
dissolved in the same solution and the relative delivery rates of precursors are defined by the
solution composition. There are only a couple of reports in the literature on DLI-CVD of nickel
ferrite, e.g., using metal thd (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) precursors.[83,85] In
spite of reported polycrystalline/epitaxial growth of nickel ferrite on different substrates (Si(100)
and MgO(100)), the as-deposited thin film characteristics (morphology and magnetic properties)
are far from satisfactory as compared to bulk nickel ferrite. One of the DLI-CVD experimental
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