Ald processes development for hybrid nanodevices-like nanostructures
Moreno Araneda, Mabel Andrea
The development of new and innovative atomic structures displaying multifunctional properties goes together with progress in advanced processes which enable atomic level control. One leading deposition technique is Atomic layer deposition (ALD), which has emerged as a powerful tool for bond-specific functionalization and the growth of stoichiometric films over wafer scale and high area uniformity. ALD offers a wide range of functionalization routes by means of four processes such as vapor phase metalation (VPM), multiple pulsed vapor-phase infiltration (MPI), ALD and molecular layer deposition (MLD). As an example of VPM on soft molecules, Zn metalation on Enterobactin (H6EB) and FeEnterobactin (FeH3EB) were studied experimentally and theoretically. Thus, we showed that the VPM process could become a route to functionalize soft organic molecules with potential applications in the pharmaceutical field. Extending Zn metalation-VPM growth to hybrid nanostructures, in this case ML-(NH4)V7O16. nanostructured square and Mw-H2Ti3O7 nanotubes. Zn metalation-VPM process provides a way to functionalize soft nanostructured materials in order to change their crystal structure and thereby their magnetic and optical properties, without affect their morphology. The use of DEZn/H2O in MPI, promotes the nucleation of ZnO nanoparticles around the nanotube (cactus-like) affecting the morphology and surface properties. It was found that the electronic energy gap decreases with increasing Zn content, making the (ZnO)Ti3O7 nanoparticle/nanotube nanocomposites potentially useful as photoanode for dye-sensitized solar cells (DSCs) and sensors. The ALD growth of uniform MxOy thin films where M stands for V, Mn, Sn or Zn was undertaken. The preliminary results show successful deposition of ¿-MnO2, ¿-V2O5, SnxOy and ZnO stoichiometric films, uniform over large areas. This points towards the possible growth of these oxides which can be considered as energy materials. Finally, the growth of alucone thin films (AlO-T and AlO-A, T: terephthalate and A: adipate) by ALD and MLD was explored. Stoichiometric thin films with large area uniformity were obtained in both cases. The use of bifunctional monomers (aromatic and aliphatic carboxylate) in the growth of AlO-T and AlO-A thin films leads to a lamellar phase and to an amorphous one, respectively. The structure of AlO-T is obtained by optimizing four models and correlating experimental data with DFT calculations. The analysis of the electronic band gap using frontier orbital (HOMO-LUMO), alongside the uniform LiPF6 distribution through the AlO-T, point to future studies of AlO-T for anode and electrolyte nanomembranes with potential applications in carboxylates-based energy storage concepts. Thus, in this thesis we have shown the versatility of ALD processes to realize novel thin films and pursue various functionalization strategies.