Mechanical and Optical Properties of Cr₂O₃ Thin Films Grown by Atomic Layer Deposition Method Using Cr(thd)₃ and Ozone

Abstract

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 (TG) from 200 to 300 °C. X-ray amorphous films were deposited at a TG ≤ 225 °C, whereas at higher temperatures (TG ≥ 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 TG 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 TG; however, doping the Cr2O3 with Ti decreased its band gap energy value from 3.1 to 2.2 eV.

Keywords

• chromium oxide
• thin films
• atomic layer deposition
• Ti-doped Cr₂O₃
• mechanical properties
• optical properties