MOCVD of LaAlO3 films from a molten precursor mixture: Characterization of liquid, gas, and deposited phases

The capability of "second-generation" precursors to act as a solvent of other precursor species, thus yielding a molten multicomponent source, has been investigated in detail. In particular, this novel approach has been applied to the MOCVD process of high quality, epitaxial LaAlO3 thin films on SrTiO3 (100) substrates. The adopted in-situ strategy involves a molten mixture consisting of the La(hfa)(3) O diglyme (Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, diglyme = bis(2-methoxyethyl)ether) precursor which acts as a solvent for the Al(acac)(3) (Hacac = acetylacetone). Thermal analyses and "in situ" Fourier transform infrared (FTIR) spectra of the gas phase proved that the molten multi-component source possesses suitable stability during vaporization and mass transport processes. The LaAlO3 films have smooth surfaces and are epitaxially grown.