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Advanced Semiconductor Physics EE 698D Fall 2004 SUMMARY. Topics Covered. Semiconductor Bandstructure & Effective Mass Approximation Phonons/Lattice Vibrations Electronic Transport Optical Properties Quantum Confined Structures & Device Applications. Semiconductor Bandstructure.
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Advanced Semiconductor Physics EE 698D Fall 2004 SUMMARY
Topics Covered • Semiconductor Bandstructure & Effective Mass Approximation • Phonons/Lattice Vibrations • Electronic Transport • Optical Properties • Quantum Confined Structures & Device Applications
Semiconductor Bandstructure Silicon GaAs GaN
Bandstructure – k.p • Most of the action happens very close to the CB & VB edges • k.p theory ideal to handle such cases From Notes
Bandstructure – more accurate methods • Empirical Pseudopotential Method • LCAO methods Silicon GaAs
Phonons / Lattice Vibrations Phonon Dispersion of a typical semiconductor
Transport – Depends on Bandstructure, Phonons, Defects Example : GaN
Transport – Scattering and Velocity – field curves • Low-field: Mobility • High field – Velocity Saturation, Optical Phonon emission
Theoretical Formalism – Contd… FERMI’S GOLDEN RULE
Transport in a Silicon MOSFET Electron Distribution in k-space Electron Distribution in Real-Space
Ballistic Transport – Electrons as waves Electrons flow and “diffract” like Waves on surface of water…
Light in periodic structures… Photonic Bandgap Crystals
Quantum Confined Structures Nanotubes – 1D (Quantum Wires) Epitaxial 0-D (Quantum Dots) Nanowire Superlattices Nanowire “Combs”
Bulk Semiconductor – Device Applications Today’s HBT The First Transistor (1947) Today’s MOSFET
Quantum – Well Devices GaN HEMTs High-electron Mobility Transistors (HEMTs) GaAs Laser Diodes
Quantum Well Devices – GaN Solid State Lighting Blu-Ray DVD (GaN QW Laser) White LEDs - The New Bulbs!
Superlattices – Device Applications Quantum Cascade Lasers
Quantum Well Devices : Organic Semiconductors Flexible Displays (Based on optical transitions in organic QW- structures)
Quantum Wire Device Applications Nanowire Laser Arrays Nanotube FETs
Quantum Dot Applications Nanocrystal (Quantum-Dot) Luminescence Spectra Quantum confinement changes emission wavelengths!
Quantum Dot Applications Today’s Nanocrystals Bio-Applications Stained Glass – Uses quantum-dot dispersion In Glass (19th-century)!
And Finally… The NEW Christmas Lights! Hope you take away from this class the Excitement of this field …