Self-limiting nature in atomic-layer epitaxy of rutile thin films from TiCl4 and H2O on sapphire (0 0 1) substrates

The atomic-layer epitaxy of rutile thin films on sapphire (0 0 1) substrates was studied in the controlled growth of titanium oxide films by sequential surface chemical reactions using sequentially fast pressurized titanium tetrachloride (TiCl4) and water (H2O) vapor pulses. Optical constants and thicknesses of these rutile films were investigated in terms of vapor pressure using a variable-angle spectroscopic ellipsometer. As a result, the self-limiting nature in the atomic-layer epitaxy of rutile thin films was demonstrated clearly under various conditions of dosing reactant vapors, where growth rates were almost constant at approximately 0.077 nm/cycle (0.77 nm/min) and refractive indices were also constant at 2.59.