Cr₂O₃ thin films were grown on a Si (1 0 0) substrate using Cr(thd)₃ and O₃ by atomic layer deposition (ALD) at substrate temperatures (T_G) from 200 to 300 °C. X-ray amorphous films were deposited at a T_G ≤ 225 °C, whereas at higher temperatures (T_G ≥ 250 °C), the eskolaite phase was observed in the films. The growth rate of the films increased from 0.003 to 0.01 nm/cycle by increasing T_G from 200 to 275 °C. The relatively low growth rate of Cr(thd)₃—O₃ makes it appropriate for the ALD of precisely controllable solid solution-type ternary-component thin films. The Ti-doped Cr₂O₃ film showed higher hardness (16.7 GPa) compared with that of the undoped film (12.8 GPa) with similar thickness. The band gap values of the pure Cr₂O₃ corresponding to the indirect transition model showed no dependence on T_G; however, doping the Cr₂O₃ with Ti decreased its band gap energy value from 3.1 to 2.2 eV.

Structural, mechanical, and optical properties of atomic layer deposited ternary (Cr _{1− x} Al _x ) ₂ O ₃ films on sapphire substrates were compared with those of binary oxide films.