Subject 7 2nd lecture Electronic optical prop devices

Subject 7 2nd lecture Electronic optical prop devices -...

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Week (2 meetings/wk) Contents (wk starting 1/25) Introduction ; Characterizing nanoscale structures (2/1) Processing I : Microfabrication, IC and IC compatible; Thermodynamics : effects of small systems (2/8) Blizzard of 2010 (2/15) Nanoporous materials : Au fuel cell and catalysis (Erlebacher); Processing II : Nanoparticles (Searson) (2/22) Kinetics , surface diffusion, surface smoothing. Mechanical properties of nanostructured materials (3/1) Electronic properties and devices : scattering, transport, mobility, mean free path, quantum confinement (dots and wells) (3/8) Bio nanosystems & properties (Mao); Nano in fluids (Cammarata) (3/15) Spring vacation (3/22) Nanostructures and devices for optical properties (3/29) Magnetic nanostructures/properties (4/5) Nanoscale reactive multilayers Student project presentations start (4/12) Student project presentations (4/19) Student project presentations (4/26) Student project presentations (5/3) Student project presentations Revised syllabus
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When feature sizes approach “nano”… Subject 7-2 Subject 7-2 Electronic/optical properties Electronic/optical properties devices devices
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Three important driving forces in nanotechnology Three important driving forces in nanotechnology Decreased feature size for more components per unit area (for speed, volume, weight, portability, e.g. digital camera) Novel size-dependent properties when feature sizes < a characteristic length (e.g., tunneling) Unusual interplay now possible, b/t materials at nm length scale (e.g. interlayer coupling in spin valve read heads in magnetic hard drives) Subject 9
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How do these play out for electronic devices ? How do these play out for electronic devices ? Size-dependent properties This is especially relevant to EOM properties Characteristic lengths electronic/optical: < exciton Bohr radius (a few nm) => Quantum confinement
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Size-dependent properties III: Size-dependent properties III: Quantum Confinement Quantum Confinement
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Quantum confinement Quantum confinement (a) GaAs layer sandwiched between AlGaAs layers, (b) GaAs region surrounded by AlGaAs, and (c) corresponding band diagram. (AlGaAs has a wider energy gap than GaAs.)
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Quantum Confinement Quantum Confinement leading to energy level splitting and gap changes leading to energy level splitting and gap changes Exciton: quasiparticle consisting of a bound state of e- and hole, i.e., Coulomb-correlated pair
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This note was uploaded on 03/30/2010 for the course EN 510.422 taught by Professor Dr.evanma during the Spring '10 term at Johns Hopkins.

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Subject 7 2nd lecture Electronic optical prop devices -...

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