Nanofabrication

1. Nanofabrication H. Hau Wang Argonne National Laboratory Materials Science Division hau.wang@anl.gov Symposium on Digital Fabrication Aug 12, 2005

2. Why going Nano? 1 nm = 10-9 m • Chemistry – higher reactivity High surface area – Good for chemical and biochemical sensors Higher sensitivity and faster response time Good for heterogeneous catalysis The larger the surface area, the higher the reactivity. High level of reaction control • Material – better mechanical strength UNCD Ultra-nano-crystalline diamond (ANL/CNM) Ultra-thin and tough coating - prolong equipment life time Carbon-nanotubes – Ultra-high mechanical strength • Physics – quantum confined phenomena anddesigned physical properties Quantum dots, Near field optics, plasmonics High density magnetic storage – nanoclusters Ideal spring nanomagnet - High magnetization and coercivity

3. Nanofabrication – current status • Top-down Fabrication techniques e-beam lithography FIB – focused ion beam DPN – dip pen nanolithography Requires major facilities, control below 100 nm is a challenge, can not obtain high aspect ratio. • Bottom-up Synthesis – The nano-scaled objects are limited to simple geometrical shape: sphere, cube, triangle, thin film, wire, tube, etc. – No standard 3D morphological control – Handling and Alignment are difficult • Lithographically assisted self-assembly – Combining top-down and bottom-up 1 x 1 mm2 AFM image of self-assembled PEG-PMMA thin film showing partially ordered structure 5 x 5 mm2 AFM image of as-prepared AAO membrane showing domain boundary

4. Nanotubes • AAO/Al2O3/V2O5 nanostructure has been prepared for heterogeneous catalysis studies. • Pd nanotubes showed very good hydrogen sensing capability. Before ALD Cross-Section of Coated AAO 200 nm Bi NT After ALD

5. Nanoparticles • Au, Co, Co/Pt Nanoparticles – Magnetic storage (X. M. Lin et al.)

6. Dynamics of Monolayer Nanocrystal Self-assembling Process in Liquid Film To understand the dynamics of highly ordered nanocrystal monolayer through evaporation of a nanocrystal colloidal droplet. (J. Phys. Chem. B 2001, 105, 3353) Grazing Incidence Small Angle X-ray Scattering (GISAXS) • Kinetic effects can play an important role in nanocrystal self-assembly. • Fast initial evaporation rate can induce nanocrystals accumulate at the liquid-air interface and undergo a 3D to 2D structural transition to form highly ordered nanocrystal monolayer. Xiao-Min Lin Suresh Narayanan, Jin Wang MSD/CHM Advanced Photon Source

7. FM1 (Co) Parallel R NM (Cu) AP AP H FM2 (Co) Parallel DR/R 50 nm Au Nanowires • Various metallic (Au, Ag, Cu, etc.), superconductive (Pb), ferromagnetic (Co, Ni, etc.) nanowires have been made with anodized aluminum oxide (AAO) templates. • Multi-segmented (Co/Cu), (Au/Ni – Mirkin, Science 2005) nanowires have been prepared with pulsed electro-deposition. • Multi-segmented SiNi/Si/SiNi nanowires have been fabricated into integrated nanowire circuits. (Lieber, Nature 2005) http://WWW.anl.gov/ Materials Science Division, MSD Center for Nanoscale Materials, CNM Co 20 nm/Cu 20 nm M H