AVS 55th International Symposium & Exhibition | |
Thin Film | Monday Sessions |
Session TF+NC-MoM |
Session: | ALD of Hybrid Materials and ALD on 3D Nanostructures |
Presenter: | Q. Peng, North Carolina State University |
Authors: | Q. Peng, North Carolina State University X.Y. Sun, North Carolina State University J.C. Spagnola, North Carolina State University R.J. Spontak, North Carolina State University C. Saquing, North Carolina State University S.A. Khan, North Carolina State University G.N. Parsons, North Carolina State University |
Correspondent: | Click to Email |
Three-dimensional (3D) macrostructures consisting of well-defined nanoscale elements with controlled properties have attracted significant interest for a range of fields. To date, large-scale fabrication of these 3D macrostructures remains an important outstanding challenge. We are currently exploring atomic layer deposition on a variety of nano- and micro-scale fiber systems for fabrication of macro size 3D structures with molecular-scale control. Recently, we have applied low temperature (< 80 degree C) Al2O3 and ZnO ALD processes onto 3D polyvinyl alcohol electrospun fiber matrix templates to form Al2O3, ZnO and Al2O3/ZnO/Al2O3 multilayer nanotubes with controlled tube wall thickness. SEM, TEM and XRD have been used to probe the structure and crystal structure of the materials as a function of deposition parameters and post-deposition calcination and annealing. We find that upon annealing at 700 degree C, the ZnO and Al2O3 layers in the Al2O3/ZnO/Al2O3 coaxial structures can react with each other, due to the solid-state reaction and diffusion process between ZnO/Al2O3 (Kirkendall effect), to form pairs of coaxial ZnAl2O4 hollow nanotubes separated by a nanoscale gap. Moreover, by controlling the thickness of the individual Al2O3 and ZnO layers and the ZnO/Al2O3 thickness ratio, the final thickness of the nanotubes and the separation nanogap can be tuned to form a variety of well-defined tube-in-tube nanosystems. Under some conditions, unreacted ZnO layers can remain after annealing, resulting in multi-compositional structures with segregated voids. These results show the feasibility of extending reactivity of ALD thin films and Kirkendall effect to form a range of quasi-one-dimensional nanostructures for a variety of potential applications.