Tailored height gradients in vertical nanowire arrays via mechanical and electronic modulation of metal-assisted chemical etching
Otte Ortiz, Marinus Albertus (Institut Català de Nanociència i Nanotecnologia)
Solís Tinoco, Verónica Iraís (Institut Català de Nanociència i Nanotecnologia)
Prieto Recio, Pilar (Instituto de Microelectrónica de Madrid)
Borrisé, Xavier (Institut Català de Nanociència i Nanotecnologia)
Lechuga, Laura M (Institut Català de Nanociència i Nanotecnologia)
González, M. U. (Instituto de Microelectrónica de Madrid)
Sepúlveda, Borja (Institut Català de Nanociència i Nanotecnologia)

Date:	2015
Abstract:	In current top-down nanofabrication methodologies the design freedom is generally constrained to the two lateral dimensions, and is only limited by the resolution of the employed nanolithographic technique. However, nanostructure height, which relies on certain mask-dependent material deposition or etching techniques, is usually uniform, and on-chip variation of this parameter is difficult and generally limited to very simple patterns. Herein, a novel nanofabrication methodology is presented, which enables the generation of high aspect-ratio nanostructure arrays with height gradients in arbitrary directions by a single and fast etching process. Based on metal-assisted chemical etching using a catalytic gold layer perforated with nanoholes, it is demonstrated how nanostructure arrays with directional height gradients can be accurately tailored by: (i) the control of the mass transport through the nanohole array, (ii) the mechanical properties of the perforated metal layer, and (iii) the conductive coupling to the surrounding gold film to accelerate the local electrochemical etching process. The proposed technique, enabling 20-fold on-chip variation of nanostructure height in a spatial range of a few micrometers, offers a new tool for the creation of novel types of nano-assemblies and metamaterials with interesting technological applications in fields such as nanophotonics, nanophononics, microfluidics or biomechanics. Based on metal-assisted chemical etching using a catalytic gold layer perforated with nanoholes, it is demonstrated how high aspect-ratio nanostructure arrays with directional height gradients can be accurately tailored by: i) control of mass transport through the nanohole array, ii) mechanical properties of the perforated metal layer, and iii) conductive coupling to the surrounding gold film to accelerate the local electrochemical etching process. The proposed technique, enabling 20-­-fold on-­-chip variation of nanostructure height in a spatial range of a few microns, offers a new tool for the creation of novel types of nano-­-assemblies and metamaterials with interesting technological applications in fields such as nanophotonics, nanophononics, microfluidics or biomechanics.
Grants:	Ministerio de Economía y Competitividad MAT2011-12645-­E Ministerio de Economía y Competitividad TEC2012-­34280 Ministerio de Economía y Competitividad MAT2011-29194-C02-­01 Ministerio de Economía y Competitividad MAT2013-48628-­R Ministerio de Economía y Competitividad SEV-­2013-­0295
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Nanofabrication ; Height gradients ; High aspect-­ratio vertical nanowires ; Metal assisted chemical etching ; Metamaterials
Published in:	Small, Vol. 11, Issue 33 (September 2015) , p. 4201-4208, ISSN 1613-6829

DOI: 10.1002/smll.201500175

Postprint 32 p, 5.3 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles