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A Brief Introduction to Nanotechnology :
Not for distribution A Brief Introduction to Nanotechnology Christian A. Zorman Department of Electrical Engineering and Computer Science Case Western Reserve Univesity Cleveland, Ohio 44106 Christian.
Nanotechnology Defined :
Not for distribution Nanotechnology Defined “The development and use of devices that have a size of only a few nanometres.” physics.about.com “Research and technology development at the atomic, molecular or macromolecular level in the length scale of approximately 1 - 100 nm range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.” nano.gov “Branch of engineering that deals with things smaller than 100 nm (especially with the manipulation of individual molecules).” hyperdictionary.com “Nanotechnology, or, as it is sometimes called, molecular manufacturing, is a branch of engineering that deals with the design and manufacture of extremely small electronic circuits and mechanical devices built at the molecular level of matter.” whatis.com “The art of manipulating materials on an atomic or molecular scale especially to build microscopic devices.” Miriam Webster Dictionary
Perspective of Length Scale :
Not for distribution Perspective of Length Scale Size of an atom 1 m 1 mm 1 mm 1 nm Humans Car Butterfly Gnat 1 km Boeing 747 Laptop Wavelength of Visible Light Micromachines Width of DNA Smallest feature in microelectronic chips Proteins Biological cell Nucleus of a cell Aircraft Carrier Size of a Microprocessor Nanostructures & Quantum Devices Top Down Bottom Up Resolving power of the eye ~ 0.2 mm http://dod.gov/news/Dec1997/n12301997_9712302.html
Perspective of Size :
Not for distribution Perspective of Size Water molecules – 3 atoms Protein molecules – thousands of atoms DNA molecules – millions of atoms Nanowires, carbon nanotubes – millions of atoms Carbon nanotube water molecule Protein molecule Molecule of DNA iacr.bbsrc.ac.uk/notebook/ courses/guide/dnast.htm phys.psu.edu/~crespi/research/_carbon.1d/public student.biology.arizona.edu/.../ group2/crystallography.htm
How Small is a nm? :
Not for distribution How Small is a nm? 1 µm = one millionth of a meter 1 nm = one billionth of a meter ≈ 1/50,000 thickness of a hair! ≈ a string of 3 atoms If we shrunk all distances by 110,000,000,000 X The sun and earth would be separated by 1 m A football field would be 1 nm Human hair thickness ~ 50 µm 110,000,000 km 110 m
Surface vs. Volume :
Not for distribution Surface vs. Volume Si has a diamond structure with a = 5.43 Å A Si nanocube 10 nm on a side is composed of: ~6250 unit cells ~50,000 atoms Each nanocube face is composed of: ~340 unit cells per face ~680 surface atoms per face Total surface area is: ~4080 atoms (~10% surface atoms) A bulk Si film 1 µm thick on a 10 cm square: ~6.3 X 1019 unit cells ~5 X 1020 atoms ~1.4 X 1017 surface atoms (~0.03% surface atoms) a Diamond unit cell Si nanocube Bulk Si film In a nanoscale material, the surface/boundary/interface plays an important role!
More than just size… :
Not for distribution More than just size… Chemical – take advantage of large surface to volume ratio, interfacial and surface chemistry important, systems too small for statistical analysis Electronic – quantum confinement, bandgap engineering, change in density of states, electron tunneling Magnetic – giant magnetoresistance by nanoscale multilayers, change in magnetic susceptibility Interesting phenomena: STM of dangling bonds on a Si:H surface http://pubweb.acns.nwu.edu/~mhe663/
More than just size … :
Not for distribution More than just size … Interesting phenomena: Fluorescence of quantum dots of various sizes Phonon tunneling Mechanical – improved strength hardness in light-weight nanocomposites and nanomaterials, altered bending, compression properties, nanomechanics of molecular structures Optical – absorption and fluorescence of nanocrystals, single photon phenomena, photonic bandgap engineering Fluidic – enhanced flow properties with nanoparticles, nanoscale adsorbed films important Thermal – increased thermoelectric performance of nanoscale materials, interfacial thermal resistance important.
Development of Nanotechnology :
Not for distribution Development of Nanotechnology Fundamental Understanding Characterization and Experimentation Synthesis and Integration Nano to Macro Inorganic and Organic Optical with Mechanical with Electrical with Magnetic with …
Slide 10:
Not for distribution nanopedia.cwru.edu Nanotech – The next new thing?
Slide 11:
Not for distribution Ohio’s Position in Nanotechnology James Murday, Naval Research Laboratory
Nanofabrication :
Not for distribution Nanofabrication Nanofabrication can generally be divided into two categories based on the approach: “Top-Down”: Fabrication of device structures via monolithic processing on the nanoscale. “Bottom-Up”: Fabrication of device structures via systematic assembly of atoms, molecules or other basic units of matter.
Integrated Circuits and Nanotech :
Not for distribution Integrated Circuits and Nanotech The IC industry is approaching a period where nanotech approaches will be required to sustain technology growth J.D. Plummer, M.D. Deal, and P.B. Griffin, “Silicon VLSI Technology – Fundamentals, Practice and Modeling” Prentice Hall, NJ
Nanotech and Microfabrication :
Not for distribution Nanotech and Microfabrication Microfabrication is a top-down technique utilizing the following processes in sequential fashion: Film Deposition CVD, PVD Photolithography Optical exposure, PR Etching Aqueous, plasma Many of these techniques are useful, directly or indirectly in nanofabrication
Slide 15:
Not for distribution SEM showing one of the two doubly-clamped 3C-SiC beams in a device structure. The device was fabricated using top-down techniques. Length: m1.1 Width: 120 nm Thickness: 75 nm Top - Down Nanofabrication
What are Nanostructures? :
Not for distribution What are Nanostructures? At least one dimension is between 1 - 100 nm 2-D structures (1-D confinement): Thin films Planar quantum wells Superlattices 1-D structures (2-D confinement): Nanowires Quantum wires Nanorods Nanotubes 0-D structures (3-D confinement): Nanoparticles Quantum dots Dimensionality, confinement depends on structure: Bulk nanocrystalline films Nanocomposites Si0.76Ge0.24 / Si0.84Ge0.16 superlattice m2 Si Nanowire Array Multi-wall carbon nanotube
Thin Films :
Not for distribution Thin Films Nanoscale Thin Film Single “two dimensional” film, thickness < ~100 nm Electrons can be confined in one dimension; affects wavefunction, density of states Phonons can confined in one dimension; affects thermal transport Boundaries, interfaces affect transport Bulk crystal a Free standing thin film d Thin film Substrate
Thin Film Applications :
Not for distribution Thin Film Applications 100 nm sputtered YSZ film for solid oxide fuel cells Amorphous Si TFT on a SiNx passivated polyimide foil Solid Fuel Cells: (nanostructured) thin film solid electrolytes and electrodes with high conductance Thin Film Transistors for liquid crystal displays: requires high mobility and flexible substrates Gas sensing applications Thin layers in electronic devices http://bu.edu/mfg/pdf/Tuller.pdf Wagner et al, Thin Solid Films, Vol. 490, pp. 12 – 19 (2003).
Nanowires :
Not for distribution Nanowires Solid, “one dimensional” Can be conducting, semiconducting, insulating Can be crystalline, low defects Can exhibit quantum confinement effects (electron, phonon) Narrowing wire diameter results in increase in band gap Narrowing wire diameter can result in decrease in thermal conductivity New forms include core-shell and superlattice nanowires 2 m Si Nanowire Array Nanotube defined – a long cylinder with inner and outer nm-sized diameters Nanowire defined – a long, solid wire with nm diameter Si/SiGe Nanowires Abramson et al, JMEMS (2003) Wu et al, Nanoletters, Vol. 2, 83 – 86 (2002)
Nanowires Applications :
Not for distribution Nanowires Applications Field effect transistors Thermoelectric materials Light emitting diodes Detectors Sensors Nanolasers Superlattice nanowires in applications requiring superlattices 5 nm Si nanowire FET Cui et al, Nanoletters, Vol. 3, 149 – 152 (2003). Nanolaser from 100 nm CdSe nanowire
Carbon Nanotubes :
Not for distribution Carbon Nanotubes Carbon nanotube properties: One dimensional sheets of hexagonal network of carbon rolled to form tubes Approximately 1 nm in diameter Can be microns long Essentially free of defects Ends can be “capped” with half a buckyball Varieties include single-wall and multi- wall nanotubes,ropes, bundles, arrays Structure (chirality, diameter) influences properties: Semiconducting vs. metallic Thermal, electrical conductance Mechanical strength, elasticity Multi-wall carbon nanotube
Other Nanotubes… :
Not for distribution Other Nanotubes… Boron nitride nanotubes Resistance to oxidation, suited for high temperatures Young’s modulus of 1.22 TPa Semiconducting Predictable electronic properties independent of diameter and # of layers SiC nanotubes: Resistance to oxidation Suitable for harsh environments Can functionalize surface Si atoms Boron nitride nanotubes adopt various shapes (red=boron, blue=nitrogen):
Nanoparticles/Quantum Dots :
Not for distribution Nanoparticles/Quantum Dots “Zero-dimensional” particle Surface effects/chemistry important Radius < 100 nm < 106 atoms per nanoparticle Size smaller than critical length scales (e.g. mean free path, wavelength) Nano/quantum physical phenomena present “Large” nanoparticles have same structure as bulk; “small” may be different Synthesis: RF plasma, chemical, thermolysis, pulsed laser “Old” examples Stained glass – small metal oxide clusters comparable in size to the wavelength of light Photography – small colloidal silver particles for image formation molecules nanoparticles Radius of particle or cluster bulk quantum dots
Nanoparticles/Quantum Dots :
Not for distribution Nanoparticles/Quantum Dots Metalic nanoparticles aveka.com Si nanoparticle; single-crystal; hexagonal shape Bapat et al, J Appl Phys, Vol. 94, 1969 – 1974 (2003) Gradient of gold nanoparticles on a silica surface
Semiconductor Nanoparticles :
Not for distribution Semiconductor Nanoparticles Nanoparticles comprised of “bulk semiconductor” elements exhibit unique optical properties Shift in optical absorption particle toward shorter wavelengths with reduced size For particle radius > exciton radius photon induced transitions in exciton energy levels produce series of discrete optical absorption levels For particle radius < exciton radius no exciton and individual electron and hole transitions of discrete optical absorption levels observed Fluorescence at different wavelengths from a single UV light due to quantum confinement in semiconductor quantum dots nanosysinc.com
Nanoparticle Probes :
Not for distribution Nanoparticle Probes Objective: To detect and “kill” individual cancer cells before they manifest as tumors using functionalized nanoparticles 5 to 10 nm particles (small enough to interact with intracellular markers) nanoparticles are coated and functionalized with antibodies, oligonucleotides, peptide ligands and drugs Introduced to body via bloodstream “Look” for markers inside cell by MRI or deliver agent or irradiate
Nanostructured Bulk Materials :
Not for distribution Nanostructured Bulk Materials Includes: Amorphous/glassy materials (atomic scale ordering) Any material with nanostructured grain sizes (nm ordering) Nanoporous materials (nm ordering) Multilayer nanoscale thin films (nm ordering – SL period) Characteristics (Å to nano to micro) affect chemical, physical, mechanical properties, which are usually enhanced Solid formations crystalline, amorphous, polycrystalline Polycrystalline materials can be nanostructured if grain sizes < 100 nm
Nanostructured Bulk Materials Applications :
Not for distribution Nanostructured Bulk Materials Applications Manufacturing – thermal barrier coatings ceramic films problem: require lower thermal conductivity/high strength solution: nanostructured films? Other applications: Catalysts Solar cells Stronger, long lasting materials applications Electronics Batteries Sensors Flat panel displays Nanocrystalline thermal barrier coating of YSZ http://msd.anl.gov/groups/im/highlights/...ivity.html Nanocrystalline diamond coatings for field emission tips http://msd.anl.gov/groups/im/highlights/...ssion.html
A Brief Introduction to Nanotechnology :
Not for distribution A Brief Introduction to Nanotechnology Christian A. Zorman Department of Electrical Engineering and Computer Science Case Western Reserve Univesity Cleveland, Ohio 44106 Christian.
Nanotechnology Defined :
Not for distribution Nanotechnology Defined “The development and use of devices that have a size of only a few nanometres.” physics.about.com “Research and technology development at the atomic, molecular or macromolecular level in the length scale of approximately 1 - 100 nm range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.” nano.gov “Branch of engineering that deals with things smaller than 100 nm (especially with the manipulation of individual molecules).” hyperdictionary.com “Nanotechnology, or, as it is sometimes called, molecular manufacturing, is a branch of engineering that deals with the design and manufacture of extremely small electronic circuits and mechanical devices built at the molecular level of matter.” whatis.com “The art of manipulating materials on an atomic or molecular scale especially to build microscopic devices.” Miriam Webster Dictionary
Perspective of Length Scale :
Not for distribution Perspective of Length Scale Size of an atom 1 m 1 mm 1 mm 1 nm Humans Car Butterfly Gnat 1 km Boeing 747 Laptop Wavelength of Visible Light Micromachines Width of DNA Smallest feature in microelectronic chips Proteins Biological cell Nucleus of a cell Aircraft Carrier Size of a Microprocessor Nanostructures & Quantum Devices Top Down Bottom Up Resolving power of the eye ~ 0.2 mm http://dod.gov/news/Dec1997/n12301997_9712302.html
Perspective of Size :
Not for distribution Perspective of Size Water molecules – 3 atoms Protein molecules – thousands of atoms DNA molecules – millions of atoms Nanowires, carbon nanotubes – millions of atoms Carbon nanotube water molecule Protein molecule Molecule of DNA iacr.bbsrc.ac.uk/notebook/ courses/guide/dnast.htm phys.psu.edu/~crespi/research/_carbon.1d/public student.biology.arizona.edu/.../ group2/crystallography.htm
How Small is a nm? :
Not for distribution How Small is a nm? 1 µm = one millionth of a meter 1 nm = one billionth of a meter ≈ 1/50,000 thickness of a hair! ≈ a string of 3 atoms If we shrunk all distances by 110,000,000,000 X The sun and earth would be separated by 1 m A football field would be 1 nm Human hair thickness ~ 50 µm 110,000,000 km 110 m
Surface vs. Volume :
Not for distribution Surface vs. Volume Si has a diamond structure with a = 5.43 Å A Si nanocube 10 nm on a side is composed of: ~6250 unit cells ~50,000 atoms Each nanocube face is composed of: ~340 unit cells per face ~680 surface atoms per face Total surface area is: ~4080 atoms (~10% surface atoms) A bulk Si film 1 µm thick on a 10 cm square: ~6.3 X 1019 unit cells ~5 X 1020 atoms ~1.4 X 1017 surface atoms (~0.03% surface atoms) a Diamond unit cell Si nanocube Bulk Si film In a nanoscale material, the surface/boundary/interface plays an important role!
More than just size… :
Not for distribution More than just size… Chemical – take advantage of large surface to volume ratio, interfacial and surface chemistry important, systems too small for statistical analysis Electronic – quantum confinement, bandgap engineering, change in density of states, electron tunneling Magnetic – giant magnetoresistance by nanoscale multilayers, change in magnetic susceptibility Interesting phenomena: STM of dangling bonds on a Si:H surface http://pubweb.acns.nwu.edu/~mhe663/
More than just size … :
Not for distribution More than just size … Interesting phenomena: Fluorescence of quantum dots of various sizes Phonon tunneling Mechanical – improved strength hardness in light-weight nanocomposites and nanomaterials, altered bending, compression properties, nanomechanics of molecular structures Optical – absorption and fluorescence of nanocrystals, single photon phenomena, photonic bandgap engineering Fluidic – enhanced flow properties with nanoparticles, nanoscale adsorbed films important Thermal – increased thermoelectric performance of nanoscale materials, interfacial thermal resistance important.
Development of Nanotechnology :
Not for distribution Development of Nanotechnology Fundamental Understanding Characterization and Experimentation Synthesis and Integration Nano to Macro Inorganic and Organic Optical with Mechanical with Electrical with Magnetic with …
Slide 10:
Not for distribution nanopedia.cwru.edu Nanotech – The next new thing?
Slide 11:
Not for distribution Ohio’s Position in Nanotechnology James Murday, Naval Research Laboratory
Nanofabrication :
Not for distribution Nanofabrication Nanofabrication can generally be divided into two categories based on the approach: “Top-Down”: Fabrication of device structures via monolithic processing on the nanoscale. “Bottom-Up”: Fabrication of device structures via systematic assembly of atoms, molecules or other basic units of matter.
Integrated Circuits and Nanotech :
Not for distribution Integrated Circuits and Nanotech The IC industry is approaching a period where nanotech approaches will be required to sustain technology growth J.D. Plummer, M.D. Deal, and P.B. Griffin, “Silicon VLSI Technology – Fundamentals, Practice and Modeling” Prentice Hall, NJ
Nanotech and Microfabrication :
Not for distribution Nanotech and Microfabrication Microfabrication is a top-down technique utilizing the following processes in sequential fashion: Film Deposition CVD, PVD Photolithography Optical exposure, PR Etching Aqueous, plasma Many of these techniques are useful, directly or indirectly in nanofabrication
Slide 15:
Not for distribution SEM showing one of the two doubly-clamped 3C-SiC beams in a device structure. The device was fabricated using top-down techniques. Length: m1.1 Width: 120 nm Thickness: 75 nm Top - Down Nanofabrication
What are Nanostructures? :
Not for distribution What are Nanostructures? At least one dimension is between 1 - 100 nm 2-D structures (1-D confinement): Thin films Planar quantum wells Superlattices 1-D structures (2-D confinement): Nanowires Quantum wires Nanorods Nanotubes 0-D structures (3-D confinement): Nanoparticles Quantum dots Dimensionality, confinement depends on structure: Bulk nanocrystalline films Nanocomposites Si0.76Ge0.24 / Si0.84Ge0.16 superlattice m2 Si Nanowire Array Multi-wall carbon nanotube
Thin Films :
Not for distribution Thin Films Nanoscale Thin Film Single “two dimensional” film, thickness < ~100 nm Electrons can be confined in one dimension; affects wavefunction, density of states Phonons can confined in one dimension; affects thermal transport Boundaries, interfaces affect transport Bulk crystal a Free standing thin film d Thin film Substrate
Thin Film Applications :
Not for distribution Thin Film Applications 100 nm sputtered YSZ film for solid oxide fuel cells Amorphous Si TFT on a SiNx passivated polyimide foil Solid Fuel Cells: (nanostructured) thin film solid electrolytes and electrodes with high conductance Thin Film Transistors for liquid crystal displays: requires high mobility and flexible substrates Gas sensing applications Thin layers in electronic devices http://bu.edu/mfg/pdf/Tuller.pdf Wagner et al, Thin Solid Films, Vol. 490, pp. 12 – 19 (2003).
Nanowires :
Not for distribution Nanowires Solid, “one dimensional” Can be conducting, semiconducting, insulating Can be crystalline, low defects Can exhibit quantum confinement effects (electron, phonon) Narrowing wire diameter results in increase in band gap Narrowing wire diameter can result in decrease in thermal conductivity New forms include core-shell and superlattice nanowires 2 m Si Nanowire Array Nanotube defined – a long cylinder with inner and outer nm-sized diameters Nanowire defined – a long, solid wire with nm diameter Si/SiGe Nanowires Abramson et al, JMEMS (2003) Wu et al, Nanoletters, Vol. 2, 83 – 86 (2002)
Nanowires Applications :
Not for distribution Nanowires Applications Field effect transistors Thermoelectric materials Light emitting diodes Detectors Sensors Nanolasers Superlattice nanowires in applications requiring superlattices 5 nm Si nanowire FET Cui et al, Nanoletters, Vol. 3, 149 – 152 (2003). Nanolaser from 100 nm CdSe nanowire
Carbon Nanotubes :
Not for distribution Carbon Nanotubes Carbon nanotube properties: One dimensional sheets of hexagonal network of carbon rolled to form tubes Approximately 1 nm in diameter Can be microns long Essentially free of defects Ends can be “capped” with half a buckyball Varieties include single-wall and multi- wall nanotubes,ropes, bundles, arrays Structure (chirality, diameter) influences properties: Semiconducting vs. metallic Thermal, electrical conductance Mechanical strength, elasticity Multi-wall carbon nanotube
Other Nanotubes… :
Not for distribution Other Nanotubes… Boron nitride nanotubes Resistance to oxidation, suited for high temperatures Young’s modulus of 1.22 TPa Semiconducting Predictable electronic properties independent of diameter and # of layers SiC nanotubes: Resistance to oxidation Suitable for harsh environments Can functionalize surface Si atoms Boron nitride nanotubes adopt various shapes (red=boron, blue=nitrogen):
Nanoparticles/Quantum Dots :
Not for distribution Nanoparticles/Quantum Dots “Zero-dimensional” particle Surface effects/chemistry important Radius < 100 nm < 106 atoms per nanoparticle Size smaller than critical length scales (e.g. mean free path, wavelength) Nano/quantum physical phenomena present “Large” nanoparticles have same structure as bulk; “small” may be different Synthesis: RF plasma, chemical, thermolysis, pulsed laser “Old” examples Stained glass – small metal oxide clusters comparable in size to the wavelength of light Photography – small colloidal silver particles for image formation molecules nanoparticles Radius of particle or cluster bulk quantum dots
Nanoparticles/Quantum Dots :
Not for distribution Nanoparticles/Quantum Dots Metalic nanoparticles aveka.com Si nanoparticle; single-crystal; hexagonal shape Bapat et al, J Appl Phys, Vol. 94, 1969 – 1974 (2003) Gradient of gold nanoparticles on a silica surface
Semiconductor Nanoparticles :
Not for distribution Semiconductor Nanoparticles Nanoparticles comprised of “bulk semiconductor” elements exhibit unique optical properties Shift in optical absorption particle toward shorter wavelengths with reduced size For particle radius > exciton radius photon induced transitions in exciton energy levels produce series of discrete optical absorption levels For particle radius < exciton radius no exciton and individual electron and hole transitions of discrete optical absorption levels observed Fluorescence at different wavelengths from a single UV light due to quantum confinement in semiconductor quantum dots nanosysinc.com
Nanoparticle Probes :
Not for distribution Nanoparticle Probes Objective: To detect and “kill” individual cancer cells before they manifest as tumors using functionalized nanoparticles 5 to 10 nm particles (small enough to interact with intracellular markers) nanoparticles are coated and functionalized with antibodies, oligonucleotides, peptide ligands and drugs Introduced to body via bloodstream “Look” for markers inside cell by MRI or deliver agent or irradiate
Nanostructured Bulk Materials :
Not for distribution Nanostructured Bulk Materials Includes: Amorphous/glassy materials (atomic scale ordering) Any material with nanostructured grain sizes (nm ordering) Nanoporous materials (nm ordering) Multilayer nanoscale thin films (nm ordering – SL period) Characteristics (Å to nano to micro) affect chemical, physical, mechanical properties, which are usually enhanced Solid formations crystalline, amorphous, polycrystalline Polycrystalline materials can be nanostructured if grain sizes < 100 nm
Nanostructured Bulk Materials Applications :
Not for distribution Nanostructured Bulk Materials Applications Manufacturing – thermal barrier coatings ceramic films problem: require lower thermal conductivity/high strength solution: nanostructured films? Other applications: Catalysts Solar cells Stronger, long lasting materials applications Electronics Batteries Sensors Flat panel displays Nanocrystalline thermal barrier coating of YSZ http://msd.anl.gov/groups/im/highlights/...ivity.html Nanocrystalline diamond coatings for field emission tips http://msd.anl.gov/groups/im/highlights/...ssion.html
