Mardi 9 juillet à 14h
Séminaire du Pr. Helmut BAUMGART
Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529, USA
Applied Research Center at Jefferson National Accelerator Laboratory, Newport News, Virginia 23606, USA
Atomic Layer Deposition (ALD) Technology: A Versatile Toolbox for Nanotechnology Engineering
Abstract
Atomic Layer Deposition (ALD) Technology: A Versatile Toolbox for Nanotechnology Engineering
Helmut Baumgart 1, 2
1Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529, USA
2Applied Research Center at Jefferson National Accelerator Laboratory, Newport News, Virginia 23606, USA
The potential of achieving novel device architectures with nanomaterials has attracted renewed attention in template replication techniques for nanotechnology engineering. Lithographically defined microporous templates in conjunction with the atomic layer deposition (ALD) technique enable remarkable control of complex novel nested nanotube structures. Porous anodic aluminium oxide (AAO) and macroporous Si are very attractive as a template for cost-saving and very efficient nanofabrication. In this presentation we investigate templating techniques by utilizing atomic layer deposition (ALD) to create far more complex nested multiple-walled nested nanotube structures within porous silicon templates with applications in photovoltaics, gas sensors, detectors, photonic crystals and microfluidic devices. ALD is a thin film growth technology based on a sequence of two self-limiting reactions between gaseous precursor molecules and a solid surface to deposit films in a layer-by-layer with atomic resolution. Since gas phase reactants are utilized, conformal coatings can be achieved with very high aspect ratio geometries on three-dimensional (3D) porous structures. Such template guided, conformal depositions by ALD can produce concentric nested multilayered nanotubes and thus enable the fabrication of multilayered nanotube architectures inside the nanopore templates. In this presentation we demonstrate precise control of the 3-dimensional parameters such as thickness, spacing and height of the nested nanotube structures by ALD. Among many interesting applications such porous templates can enable electroosmotic pumps, which in turn can benefit from ALD. Electroosmotic flow (EOF) micropumps which use electroosmosis to transport liquids have been widely used in microfluidic applications. The EOF is proportional to the zeta potential of the charged surface of the channel wall. This phenomenon is based on the fact that upon contact with a liquid an electrically charged solid surface causes a rearrangement of the local free ions in the aqueous solution to produce a thin region of nonzero net charge density near the interface. Zeta potential (ζ) modulation for the development of electroosmotic pumps in nanoporous templates can be readily accomplished by ALD technology affecting the performance of microfluidic devices. The combination of insulating oxides, semiconducting materials, and metals in combination with template replication and ALD technology can provide the genesis for various types of novel applications and eventually provide unique and advanced levels of multifunctional nanoscale devices.
