| Atomic layer deposition involving TDMATi and H2O precursors is used to grow TiO2 thin films in a homemade hot-wall, flowtube reactor.;Process optimization and film properties are studied for films grown on Si substrates. Spectroscopic ellipsometry indicates an optimal growth rate at a substrate temperature of 200°C. RBS shows a consistent coverage of Ti atoms over a large cycle range. X-ray spectroscopy reveals that the films contain very little bulk contamination and are slightly over-oxidized. FTIR and X-ray diffraction spectra show that as-deposited films are amorphous and form into the rutile crystal structure when they are annealed at 900°C. Surface roughness is measured with AFM and is shown to be 3-4% of the film's thickness.;Films are grown on GaAs substrates and ex-situ X-ray spectroscopy is used to determine interface properties. Gradual consumption of the native oxides is observed during deposition. After 250 ALD cycles, 26 A of native oxide is reduced to less than a monolayer with trace amounts of AsO x and Ga2O remaining. The consumption of the oxide is attributed to the presence of dimethylamino ligands in the TDMATi precursor. For GaAs substrates whose native oxides are etched prior to deposition, the oxides are not regrown during deposition. |
