Fully Tunable Silicon Nanowire Arrays Fabricated by Soft Nanoparticle Templating.

We demonstrate a fabrication breakthrough to produce large-area arrays of vertically aligned silicon nanowires (VA-SiNWs) with full tunability of the geometry of the single nanowires and of the whole array, paving the way toward advanced programmable designs of nanowire platforms. At the core of our fabrication route, termed "Soft Nanoparticle Templating", is the conversion of gradually compressed self-assembled monolayers of soft nanoparticles (microgels) at a water-oil interface into customized lithographical masks to create VA-SiNW arrays by means of metal-assisted chemical etching (MACE). This combination of bottom-up and top-down techniques affords excellent control of nanowire etching site locations, enabling independent control of nanowire spacing, diameter and height in a single fabrication route. We demonstrate the fabrication of centimeter-scale two-dimensional gradient photonic crystals exhibiting continuously varying structural colors across the entire visible spectrum on a single silicon substrate, and the formation of tunable optical cavities supported by the VA-SiNWs, as unambiguously demonstrated through numerical simulations. Finally, Soft Nanoparticle Templating is combined with optical lithography to create hierarchical and programmable VA-SiNW patterns.

[1]  Charles M. Lieber,et al.  A laser ablation method for the synthesis of crystalline semiconductor nanowires , 1998, Science.

[2]  Jacob T. Robinson,et al.  Vertical nanowire electrode arrays as a scalable platform for intracellular interfacing to neuronal circuits. , 2012, Nature nanotechnology.

[3]  Peng Jiang,et al.  Bioinspired Self‐Cleaning Antireflection Coatings , 2008 .

[4]  W. Richtering,et al.  Highly ordered 2D microgel arrays: compression versus self-assembly. , 2014, Soft matter.

[5]  Yadong Yin,et al.  Template‐Assisted Self‐Assembly of Spherical Colloids into Complex and Controllable Structures , 2003 .

[6]  C. Pichot,et al.  NMR investigations into heterogeneous structures of thermosensitive microgel particles , 2000 .

[7]  Simarjeet S. Saini,et al.  Nanowire Arrays: Color Generation and Refractive Index Sensing Using Diffraction from 2D Silicon Nanowire Arrays (Small 1/2014) , 2014 .

[8]  Mengyan Shen,et al.  High-density regular arrays of nanometer-scale rods formed on silicon surfaces via femtosecond laser irradiation in water. , 2008, Nano letters.

[9]  Li Jia,et al.  Micropatterning by Non‐Densely Packed Interfacial Colloidal Crystals , 2007 .

[10]  Katharina Landfester,et al.  A Convenient Method to Produce Close- and Non-close-Packed Monolayers using Direct Assembly at the Air-Water Interface and Subsequent Plasma-Induced Size Reduction , 2011 .

[11]  Paul Steinvurzel,et al.  Multicolored vertical silicon nanowires. , 2011, Nano letters.

[12]  Nicolas H Voelcker,et al.  Versatile Particle-Based Route to Engineer Vertically Aligned Silicon Nanowire Arrays and Nanoscale Pores. , 2015, ACS applied materials & interfaces.

[13]  Nicolas H. Voelcker,et al.  Engineering vertically aligned semiconductor nanowire arrays for applications in the life sciences , 2014 .

[14]  J. S. Pedersen,et al.  Small-angle neutron scattering study of structural changes in temperature sensitive microgel colloids. , 2004, The Journal of chemical physics.

[15]  M. Textor,et al.  Particle lithography from colloidal self-assembly at liquid-liquid interfaces. , 2010, ACS nano.

[16]  W. Park,et al.  Electroluminescence in n‐ZnO Nanorod Arrays Vertically Grown on p‐GaN , 2004 .

[17]  Alexander Pevzner,et al.  Si nanowires forest-based on-chip biomolecular filtering, separation and preconcentration devices: nanowires do it all. , 2012, Nano letters.

[18]  Xiuling Li,et al.  Metal assisted chemical etching for high aspect ratio nanostructures: A review of characteristics and applications in photovoltaics , 2012 .

[19]  Jacob T. Robinson,et al.  Vertical silicon nanowires as a universal platform for delivering biomolecules into living cells , 2010, Proceedings of the National Academy of Sciences.

[20]  J. Sambles,et al.  Photonic structures in biology , 2003, Nature.

[21]  Zhipeng Huang,et al.  Metal‐Assisted Chemical Etching of Silicon: A Review , 2011, Advanced materials.

[22]  Caroline A. Ross,et al.  Densely Packed Arrays of Ultra‐High‐Aspect‐Ratio Silicon Nanowires Fabricated using Block‐Copolymer Lithography and Metal‐Assisted Etching , 2009 .

[23]  Peidong Yang,et al.  Controlled growth of Si nanowire arrays for device integration. , 2005, Nano letters.

[24]  Lars Samuelson,et al.  Failure of the vapor-liquid-solid mechanism in Au-assisted MOVPE growth of InAs nanowires. , 2005, Nano letters.

[25]  Anders Kristensen,et al.  Angle-independent structural colors of silicon , 2014 .

[26]  F. Martín,et al.  Mechanical properties of vertically aligned single-crystalline silicon nanowire arrays , 2011 .

[27]  Hyunsung Park,et al.  Vertically Stacked Photodetector Devices Containing Silicon Nanowires with Engineered Absorption Spectra , 2015 .

[28]  E. Reimhult,et al.  Fabrication of nanoporous silicon nitride and silicon oxide films of controlled size and porosity for combined electrochemical and waveguide measurements , 2007 .

[29]  Wei Lu,et al.  TOPICAL REVIEW: Semiconductor nanowires , 2006 .

[30]  E. Tasciotti,et al.  Biodegradable silicon nanoneedles delivering nucleic acids intracellularly induce localized in vivo neovascularization. , 2015, Nature materials.

[31]  Lars Montelius,et al.  Nanowire Arrays Defined by Nanoimprint Lithography , 2004 .

[32]  Nicolas H. Voelcker,et al.  Maximizing Transfection Efficiency of Vertically Aligned Silicon Nanowire Arrays , 2015 .

[33]  W. Richtering,et al.  Unraveling the 3D localization and deformation of responsive microgels at oil/water interfaces: a step forward in understanding soft emulsion stabilizers. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[34]  Zhipeng Huang,et al.  Metal-assisted chemical etching of silicon and nanotechnology applications , 2014 .

[35]  Mark Oksman,et al.  Knocking down highly-ordered large-scale nanowire arrays. , 2010, Nano letters.

[36]  Joshua E. Goldberger,et al.  SEMICONDUCTOR NANOWIRES AND NANOTUBES , 2004 .

[37]  C. Mirkin,et al.  Applications of dip-pen nanolithography. , 2007, Nature nanotechnology.

[38]  Wenjun Zhang,et al.  Silicon nanowires for rechargeable lithium-ion battery anodes , 2008 .

[39]  Peidong Yang,et al.  Light trapping in silicon nanowire solar cells. , 2010, Nano letters.

[40]  Peidong Yang,et al.  Silicon Vertically Integrated Nanowire Field Effect Transistors , 2006 .

[41]  Hyunsung Park,et al.  Multispectral imaging with vertical silicon nanowires , 2013, Scientific Reports.

[42]  Bai Yang,et al.  Modulating two-dimensional non-close-packed colloidal crystal arrays by deformable soft lithography. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[43]  A. Bismuto,et al.  Electrically driven nanopillars for THz quantum cascade lasers. , 2013, Optics express.