Indian Institute of Technology Kanpur

Transcription

1 Indian Institute of Technology Kanpur Nano-Science & Technology Initiative Department of Science and Technology, India Ashutosh Sharma Department of Chemical Engineering

2 DST Unit on IITK Mesoscale Structures, Patterning and Properties with Emphasis on Soft Materials and Thin Films A state-of-the-art facility and resources for soft matter nanoscience and nanotechnology. Explore new techniques of nano-fabrication based on a creative combination of top-down including soft lithography, self-assembly and selforganization. Projects related to nano-scale understanding, fabrication and use of soft materials in coatings, NEMS, functional interfaces and bulk-nano

3 Journey of the last two years!

4 Nano-Sciences at IITK: A Mega-Passion. ructure Property Behavior Micro- and Nano Fab Lithographies, Beams Self-assembly p- wn Bottom-up Self-organization

5 Highly Multidisciplinary AND Interdisciplinary Team CORE GROUP FACULTY (~ 10) Ashutosh Sharma (soft nano fabrication; nanomechanics) Ramesh C. Budhani (magnetic nanomaterials; spintronics) V. N. Kulkarni (ion beams; fabrication) Department of Chemical Engineering Animangsu Ghatak (microfluidics; soft fabrication) Yogesh Joshi (polymer-clay nanocomposites) Nishith Verma (carbon nanocomposites) Jayant K. Singh (simulations of soft materials)

6 Department of Chemistry Sandeep Verma (self-assembly; nano-bio) Department of Materials and Metallurgical Engineering Ashish Garg (thin films; nano-structures) Department of Mechanical Engineering Shantanu Bhatacharya (nano-fabrication; MEMS) Department of Physics Rajiv Gupta (SPM; Raman) (Additional members may be co-opted depending on the focus of research---soft materials based patterning and their expertise in the Unit resources)

7 Major Facilities at Nanosciences Center About 2500 sq. ft. of class clean rooms Fabrication resources Characterization resources Collaborations: Northwestern; UIUC; UCI; Cambridge; NIST; JNCASR; IISc. Fall 2007

8 Fabrication Focused Ion Beam (Dual Beam FIB) E-Beam Lithography Broad Beam Ion Mill Maskless Photolithography Pulse laser Coating Langmuir-Blodgett Deposition NSOM UV Lithography Nanoimprint Lithography Polymer Ink-jet Printing High temperature furnaces..

9 Characterization Confocal Microscopy Micro-Raman Scanning Probe Microscopies Near-field Scanning Optical Microscopy (NSOM) Imaging and Spectroscopic Ellipsometry Profilometers (Mechanical and Optical) SEM WAXRD; SAX SQUID Optical Microscopes Contact Angle Goniometer..

10 Specific Scientific Objectives: Development of novel and facile techniques for patterning, structuring and fabrication using soft materials like polymers, gels, biological materials Development of functional interfaces such as superhydrophobic surfaces and super adhesives based on meso patterning of surfaces Attachment detachment energetics of sub-micron particles to surface and modulation by surfactants Synthesis of ordered arrays of quantum dots and nanowires including doped oxide and metal alloys and magnetic materials

11 Exploration of interfacial instabilities and failure mechanism in soft nano-structures Development of soft composites including polymernanoclay composites, thin film of meso-porous silica and its nano composites Magnetic nano particles and assemblies Development of computational nanomechanics Micro-SQUIDS and nanoscale magnetics including magnetic relaxation and supermagnetism Fabrication of carbon meso-structures based on soft fabrication techniques Microfluidic based devices and sensors

12 Current Areas of Nanosciences at IITK Fabrication using FIB, E-beam (masters; devices ) Novel soft-lithographies for large area, mesopatterning: top-down meets self-organization Nano- mechanics of soft confined materials Fabrication of novel MEMS: C-MEMS for microbattery and cell-arrays Nanocomposites: polymer, carbon, clays, silica... Meso-textured Smart functional surfaces: superwetting; smart adhesives; optical and printing surfaces

13 Interfacial/Colloidal interactions in aqueous media with polymer/surfactant adsorption Stability of soft nanostructures including structures produced by nanoimprint lithography Nanobiology: Scaffolds Nanoparticles, nanofibres and nanofilms: semiconductors, metals, polymers, carbon, ceramics, organics.. Nanostructured Magnetic Materials; spintronics

14 Nano-Patterning of Soft Materials In devices; MEMS/NEMS; Sensors; Smart Surfaces; Micro-fluidics; Super-capacitors and Batteries; Smart Adhesives; Functional Interfaces.. 1. Facilities for large area, rapid patterning: Inkjet Printing, Gravure Printing, Nanoimprint Lithography, Laser Writing, FIB, E-beam 2. Technology development for new patterning methods based on self-assembly, including e-field assisted patterning, phase change, dewetting, phase separation and stress-engineering, Nanocoatings; Fast micro/nano Texturing.

15 3. Products: Smart and Functional Surfaces by Patterning: Adhesives, Anti-reflective Coatings, Structured Colors, Anti-fouling, Difficult to fabricate Super-wetting Functional patterns Carbon patterning: MEMS, High Area Batteries Bio- and Chemical Sensors Fluidic Devices Opto-electronic Devices

16 Additional Recent Nano-Grants: Self organized patterning of polymers, British Council (UKIERI), Rs. 2.4 millions (co-pi from UK: Prof. Ullrich Steiner, Cambridge University). Carbon MEMS, part of Indo-US Center for Advanced and Futuristic Manufacturing, Indo-US Science and Technology Forum, Rs. 6.4 million (Coordinator: Prof. Amitabha Ghosh; US collaborator: Prof. Marc Madou, UCI). Manufacturing Robust Nanostructures: Materials, Methods and Metrology, Indo-US Science and Technology Forum, Frontiers of Engineering (FOE) Award for collaboration with NIST Rs. 2.5 million. (US co-pi: Christopher Soles). Mesostructured Functional Thin Films and Interfaces of Soft Materials, Department of Science and Technology, Rs. 49 million. Understanding adhesion of soft particles, Proctor & Gamble, Rs.3 million

17 Some Innovations A novel micro/nano fluidic adhesive has been prepared and shown to be vastly more effective A novel nano fabrication method based on gel miniaturization has been proposed Three novel methods for self-organized sub-micron patterning of polymers on large areas have been developed and currently being further fine-tuned for applications. A novel highly asymmetric nano-porous silica surface has been synthesized. One face of this surface is superhydrophobic and the other is hydrophilic. Potential applications are in textile and barrier coatings.

18 Application of electric fields to pattern the surfaces of soft visco-ealstic materails on sub-micron lengthscales by spatio-temporal variation of the e-field. A novel technique for synthesis of colloidal solution of nanoparticles has been developed. This pulsed laser based method allows synthesis of multicomponent oxide and metal alloy nanoparticles, which is rather difficult to achieve with the know methods. Stress tuning has been used to create novel 2- dimensional fractal networks of iron.

19 Over 70 publications in International Journals 3 patents filed and 1 disclosure 14 PhD students and several project staff trained In addition to the Unit funding ~ 15 Carores, 6 additional nano related projects ~ 7 carores generated; two industry supported Collaborations with Cambridge, NIST, Lehigh, UIC, JNCASR, Saha Institute, TRDDC, NUS.. Exciting new discoveries!!!!

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21 Grand Challenges of Soft Patterning Top-down Meets Self-Organization!! Sub-micron Features on Large areas (> cm; beyond!) Rapid (m per second!! ); (roll-to-roll?; parallel) Integration across Different Materials (hydrogels, ceramics, carbon ) Process Complexity; Resources, Cost. Patterning beyond Master: One Master, Many Slaves In-situ Tuning of Patterns Programmable Patterning

22 Functional Nano-structured Interfaces: Smart-adhesives

23 Producing High Strength Re-usable Soft Adhesives: Bio-inspired Adhesion Examples of Bioadhesives (Majumder, Ghatak & Sharma; Science, 2007) Setae of Gecko Adhesive pads of insects F G, Elastic Film t d h 0.9 J/m Microfluidic adhesive

24 Fabricating in Exotic Functional Materials: Carbon: Micro/nano Webs and C-MEMS Energy: micro battery, micro-fuel cell, super capacitor. Electronics: molecular switches, memory Biomaterials: C-MEMS. Environment: Adsorption & catalytic media With Marc Madou, UCI

25 Difficult to Fabricate Functional Materials: Carbon Energy: micro-fuel cell, micro battery, super capacitor.; Biomaterials. Functionalization: Collaborator: Marc Madou, UCI Carbon fibres Pyrolyzed Polymer structures!! Stability : Stick

26 Nano-Imprinting Challenges: Uniform high pressure/temperature Conformal contact/curved surfaces Stamp Removal Meeting the Challenges Flexible thin foil stamps Solvent vapor assisted softening of polymer films Spontaneous conformal contact by adhesive forces Soluble moulds/masters/stamps

27 Almost any polymer on any surface!! Sharma et al., Macromolecules 2006 Structural Colors by Micro-patterning: Adhesive Force Lithography with Flexible Foils: Variety of Surfaces and Materials PS polymer; 6 cm 2 Curved Hydrogel

28 Patterning Beyond Master : Pattern Miniaturization Sharma et al. 400 nm structures starting from 800 nm master

29 Patterning by Elastic Contact Instability: A New Micro/Nano Fabrication Tool pattern length scale ~ 3 H A. Positive Replica B. 2-D Bifurcation C. Compress: Negative replica D. Pull E. Feature size reduction: Thin film Sharma et al. Langmuir 2006 W ~ 2L

30 Patterning by Electric Fields: A New Fabrication Tool Sharma, Shenoy, Narayan et al., Adv Mat 2006

31 Controlled Self-organized Dewetting: A New Fabrication Tool Sharma et al.

32 Robust Nanoimprint Lithography 1. Imprinting of soft elastic films Sharma & Soles (NIST) 2. Imprinting of viscous polymeric liquid films m old (Si, Q uartz) im print m aterial substrate im print (force,uv, heat) release ISSUES: RIE etch A. Stress, strain, flow and structure relationships B. Stability and fidelity of imprinted structures C. Metrology

33 Nano-Patterning of Surfaces by Self-assembly: Sandeep Verma Adenine- Silver Metallaquartet a b HOPG J. Am. Chem. Soc. 2006, 128, Adenine- Silver Duplex HOPG a b J. Am. Chem. Soc. 2007, 129,

34 Sandeep Verma, Chemistry a b a b J. Am. Chem. Soc. 2006, 128, J. Am. Chem. Soc. 2007, 129,

35 Peptide morphologies FFPP PPFF PFFP J. Pep. Sci. 2007, 14, Chem. Eur. J. 2008, 14, Angew. Chem. 2008, 47, Angew. Chem. 2008, 47,

36 Laser Ablation Assisted Growth of Quantum Dots & Quantum Wires and Their Magnetic Properties 50 nm (a) Counts (b) (b) Diameter (nm) Ag colloid in aqueous SDS (R. Budhani et al.)

37 T G = C 2.0 μm T G = C 2.0 μm T G = C 2.0 μm (a) (b) (c) M (emu/cc) M (emu/cc) M (emu/cc) (d) (e) (f) T G = C T G = C Perpendicular In-plane Applied field (koe) CoPt Fractals and Nano dots Budhani, Rakshit et al. Appl. Phys. Lett (2006) SEM images and Perpendicular magnetization loops of 50 nm CoPt thin films deposited at various substrate temperatures at a growth rate of 0.4 Å/sec on single crystal STO (001). All the samples were post annealed for 25 minutes. Magnetization panel for the sample grown C also shows data for in-plane configuration.

38 Fabrication using FIB 1. 2-D Patterning (masks, molds, stamps) 2. 3-D Structures (AFM tips, cantilevers, devices)

39 Focused Ion Beam: Nanomachining and Beyond Nova NanoLab NOVA NANO ANOLAB AB Nano- Milling Deposition Ion Beam (Ga KeV) Spot size 7 nm Scan Generator for SEM Scan Genera tor for FIB Sample (mounted on a precision SE D/ SI D Monit or

40 EXAMPLES Micro Squid with Nb Films; Anjan Gupta et al. Holes (100 nm dia.) drilled in NbSe2 for patterning the magnetic vortex states; Satyajit Banerjee et al. Platinum electrodes separation 50 nm; I-V characteristics; Child Langmuir law at nanometer scales; S. Bhattacharjee

41 Superconducting Nano-Devices 4 V-I CHARACTERISTIC of Nb JJ (180(L) x 170(w) x 80(t) nm 3 ) 4 V-I Characteristic of Nb SQUID (H=0) 2 2 voltage in mv dv/di in ohm I C ~ 80 µa PLOT of dv/di vs I Current in ma Current in ma Voltage in mv dv/di in ohm Current in ma Current in ma SQUID Loop Area: (3.3 x 3.3) μm 2 JJs:: 200(L) x 180(w) nm 2 Maskless optical lithography + FIB milling; A. Gupta et al.

42 Carbon Cantilevers and Particles on AFM Tip AFM measurements of force-distance require dense spherical carbon particles 2-5 micron attached to the AFM tip Kulkarni et al. Sharma et al.

43 AFM Tips for Nanoindentation AFM tip of well defined shapes are required; grown Tungsten tips of hemispherical shape with the required end radius of 50 nm s [piezo displacement, nm] (z 2,s 2 ) (z 1,s 1 ) range of analysis z =(z 1 -z 2 ) s = (s 2 -s 1 ) h = (z-s) tip movement Elastic modulus [MPa] z [diflection, nm] Fig 2. Vertical displacement h [indentation depth, nm] Fig. 3 Modulus vs indentation depth Sharma, Kar, Deva et al.

44 Meso-patterning of thin polymer films by atomic force microscope assisted electrohydrodynamic nanolithography 0 th 1 st 2 nd Xie, Chung, Bandyopadhyay, Sharma, et al, J. Applied Phys. 103, (2008). selected paper in Virtual Journal of Nanoscale Science &

45 Fabrication of Small Things: Ghatak, Sharma et al. Adv Mat (2007) Top-Down Bottom-up Self-organization Miniaturization

46 Over 70 publications in International Journals 3 patents filed and 1 disclosure 14 PhD students and several project staff trained In addition to the Unit funding ~ 15 Carores, 6 additional nano related projects ~ 7 carores generated Collaborations with Cambridge, NIST, Lehigh, UIC, JNCASR, Saha Institute, TRDDC, NUS.. Exciting new discoveries!!!!

47 Best way to predict the future is to invent it.