Link between Gas Phase Reaction Chemistry and the Electronic Conductivity of Atomic Layer Deposited Titanium Oxide Thin Films.

In situ monitoring of gas phase composition reveals the link between the changing gas phase chemistry during atomic layer deposition (ALD) half-cycle reactions and the electronic conductivity of ALD-TiO2 thin films. Dimethylamine ((CH3)2NH, DMA) is probed as the main product of both the TDMAT and water vapor half-reactions during the TDMAT/H2O ALD process. In-plane electronic transport characterization of the ALD grown films demonstrates that the presence of DMA, a reducing agent, in the ALD chamber throughout each half-cycle is correlated with both an increase in the films' electronic conductivity, and observation of titanium in the 3+ oxidation state by ex situ X-ray photoelectron spectroscopy analysis of the films. DMA annealing of as-grown TiO2 films in the ALD chamber produces a similar effect on their electronic characteristics, indicating the importance of DMA-induced oxygen deficiency of ALD-TiO2 in dictating the electronic conductivity of as-grown films.