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**Advanced Semiconductor Physics**

EE 698D Fall 2004 SUMMARY

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Topics Covered Semiconductor Bandstructure & Effective Mass Approximation Phonons/Lattice Vibrations Electronic Transport Optical Properties Quantum Confined Structures & Device Applications

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**Semiconductor Bandstructure**

Silicon GaAs GaN

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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

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**Bandstructure – more accurate methods**

Empirical Pseudopotential Method LCAO methods Silicon GaAs

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**Phonons / Lattice Vibrations**

Phonon Dispersion of a typical semiconductor

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**Transport – Depends on Bandstructure, Phonons, Defects**

Example : GaN

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**Transport – Scattering and Velocity – field curves**

Low-field: Mobility High field – Velocity Saturation, Optical Phonon emission

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**Table of Scattering Processes**

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**Theoretical Formalism**

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**Theoretical Formalism – Contd…**

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**Theoretical Formalism – Contd…**

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**Theoretical Formalism – Contd…**

FERMI’S GOLDEN RULE

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**Transport in a Silicon MOSFET**

Electron Distribution in k-space Electron Distribution in Real-Space

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**Ballistic Transport – Electrons as waves**

Electrons flow and “diffract” like Waves on surface of water…

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Optical Properties

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**Light in periodic structures…**

Photonic Bandgap Crystals

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Bandgaps for light…

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**Quantum Confined Structures**

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**Quantum Confined Structures**

Nanotubes – 1D (Quantum Wires) Epitaxial 0-D (Quantum Dots) Nanowire Superlattices Nanowire “Combs”

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**Bulk Semiconductor – Device Applications**

Today’s HBT The First Transistor (1947) Today’s MOSFET

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**Quantum – Well Devices GaN HEMTs High-electron Mobility Transistors**

GaAs Laser Diodes

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**Quantum Well Devices – GaN Solid State Lighting**

Blu-Ray DVD (GaN QW Laser) White LEDs - The New Bulbs!

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**Superlattices – Device Applications**

Quantum Cascade Lasers

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**(Based on optical transitions in organic QW- structures)**

Quantum Well Devices : Organic Semiconductors Flexible Displays (Based on optical transitions in organic QW- structures)

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**Quantum Wire Device Applications**

Nanowire Laser Arrays Nanotube FETs

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**Quantum Dot Applications**

Nanocrystal (Quantum-Dot) Luminescence Spectra Quantum confinement changes emission wavelengths!

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**Uses quantum-dot dispersion**

Quantum Dot Applications Today’s Nanocrystals Bio-Applications Stained Glass – Uses quantum-dot dispersion In Glass (19th-century)!

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**And Finally… The NEW Christmas Lights!**

Hope you take away from this class the Excitement of this field …

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