Chemical Vapor Deposition

A micro-pulse ALD process is developed for fast deposition of Fe₂O₃ on both planar and high aspect ratio substrates (nanowires and AAO channels). By introducing TiO₂ co-deposition, a linear growth rate can be maintained up to 600 cycles, corresponding to a thickness of 33 nm. A controllable Ti-doping into Fe₂O₃ films is achievable by adjusting the ALD cycle ratios of TiO₂ and Fe₂O₃.

Al-doped ZnO (AZO) films are deposited by atomic layer deposition (ALD) on borosilicate glass and Si using diethylzinc and aluminum isopropoxide as Zn and Al precursors, respectively. The effects of Zn/Al ALD cycle ratio and the Al source temperature on the Al dopant concentration and resistivity of AZO films are investigated. The AZO films deposited at an Al source temperature of 120°C show the lowest resistivity.

Thin films of metal quinolines based on 8-hydroxyquinoline (q) and aluminum (Alq₃), zinc (Znq₂), and titanium (possibly Tiq₄) are deposited using ALD in the temperature range 85–200 °C. This demonstrates the ALD growth of structures based on weak Van der Waals forces. The Alq₃ material proves stable towards exposure to water during deposition. Films of both Alq₃ and Znq₂ are significantly photoluminescent active.

The mechanical properties of Al₂O₃ ALD coatings on polyamide 6 are examined by nano-indentation and flexure testing to determine the influence of a sub-surface hybrid layer formed during the ALD process. The results show the importance of the consideration of this hybrid layer on the use of these materials in future flexible electronic and encapsulation applications.

TiO₂ thin films (1.5–20 nm) are grown by ALD on electrospun WO₃ nanofibers. The WO₃/1.5 nm TiO₂ composite nanofiber has the highest photocatalytic activity, and it is a better photocatalyst under visible light when compared to bare WO₃ and Degussa TiO₂.