Composition-sensitive growth kinetics and dispersive optical properties of thin Hf_xTi_1−xO₂ (0 ≤ x ≤ 1) films prepared by the ALD method

The optical quality Hf_xTi_1−xO₂ films with a wide range of the Hf/Ti ratio were prepared on Si (100) substrates by the ALD method with the use of tetrakis(ethylmethylamido)hafnium(IV) (Hf(NC₂H₅CH₃)₄, TEMAH) and titanium(IV) chloride TiCl₄ as Hf and Ti precursors, respectively. The H₂O vapor was applied as oxygen source. The structural properties of the as-deposited and annealed films were evaluated by the XRD analysis. The Hf/Ti ratio in the films was measured by energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The dispersive optical constants were obtained by spectroscopic ellipsometry over the photon energy range of E = 1.12–4.96 eV. The specific growth kinetics is observed for 0 < x < 1. The optical constants wide-range tuning is reached in the Hf_xTi_1−xO₂ (x = 0–1) films via the chemical composition variation and annealing.