Deposition of ternary hafnium aluminum oxide alloy thin films via single-source mist chemical vapor deposition

In this study, hafnium aluminum oxide (Hf1-xAlxOy) alloy thin films were successfully deposited using a fine-channel, single-source mist chemical vapor deposition (mist-CVD) system.The precursor solution was prepared by codissolving hafnium (Hf) and aluminum (Al) precursors in methanol.Hf1-xAlxOy films with different Al compositions in the range 0 ≤ x ≤ 1 were prepared and then characterized using grazing incidence X-ray diffraction (GIXRD), spectroscopic ellipsometry, and X-ray reflectivity measurements.GIXRD analysis confirmed that the incorporation of Al in HfO2 led to the formation of amorphous alloy films (x > 0.38).Increasing the Al content in the film decreased the refractive index and mass density while widening the bandgap, reflecting the compositional change from HfO2 to Al2O3.Moreover, the properties of the mist-CVD-derived Hf1-xAlxOy films were comparable to those reported in the literature, which were prepared via conventional vacuum-based atomic layer deposition.These findings suggest that mist-CVD is a promising solution-processed and non-vacuum technique for depositing high-quality Hf1-xAlxOy alloy films.