Modeling and optimization of atomic layer deposition processes on vertically aligned carbon nanotubes.
Many energy conversion and storage devices exploit structured ceramics with large interfacial surface areas. Vertically aligned carbon nanotube (VACNT) arrays have emerged as possible scaffolds to support large surface area ceramic layers. However, obtaining conformal and uniform coatings of ceramics on structures with high aspect ratio morphologies is non-trivial, even with atomic layer deposition (ALD). Here we implement a diffusion model to investigate the effect of the ALD parameters on coating kinetics and use it to develop a guideline for achieving conformal and uniform thickness coatings throughout the depth of ultra-high aspect ratio structures. We validate the model predictions with experimental data from ALD coatings of VACNT arrays. However, the approach can be applied to predict film conformality as a function of depth for any porous topology, including nanopores and nanowire arrays.
Nanoscience for Energy Technology and Sustainability, Department of Mechanical and Process Engineering, ETH Zürich, Zürich CH-8092, Switzerland ; Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich CH-8092, Switzerland.
Nuri
N
Yazdani
Laboratory for Mechanics of Materials and Nanostructures, EMPA, Thun CH-3602, Switzerland.
Vipin
V
Chawla
Laboratory for Mechanics of Materials and Nanostructures, EMPA, Thun CH-3602, Switzerland.
Eve
E
Edwards
Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich CH-8092, Switzerland.
Vanessa
V
Wood
Nanoscience for Energy Technology and Sustainability, Department of Mechanical and Process Engineering, ETH Zürich, Zürich CH-8092, Switzerland.
Hyung Gyu
HG
Park
Laboratory for Mechanics of Materials and Nanostructures, EMPA, Thun CH-3602, Switzerland.
Ivo
I
Utke
atomic layer deposition; conformal coating guidelines; continuum diffusion model; titania, TiO2; vertically aligned carbon nanotubes