TiO2 was prepared by atomic layer deposition (ALD) using an automated thermal reactor (Gemstar XT-D; Arradiance). The reactor used N2 as a carrier gas, which was set at a constant flow of 20 sccm. TiO2 films were deposited through the noted number of deposition cycles using tetrakis(dimethylamido)titanium (TDMAT; 99%; Strem) as the Ti precursor and water as the oxidant. The TDMAT bottle was held at 75 ºC to increase the vapor pressure of the precursor. Each cycle of ALD growth was comprised of the sequence: 100 ms TDMAT pulse, 30 s reactor purge, 21 ms water pulse, 30 s reactor purge. The reactor door temperature was held at the constant temperature as noted.