1. Advanced Semiconductor Physics
EE 698D
Fall 2004
SUMMARY

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

3. Semiconductor Bandstructure
Silicon
GaAs
GaN

4. 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

5. Bandstructure – more accurate methods
Empirical Pseudopotential Method
LCAO methods
Silicon
GaAs

6. Phonons / Lattice Vibrations
Phonon Dispersion of
a typical semiconductor

7. Transport – Depends on Bandstructure, Phonons, Defects
Example : GaN

8. Transport – Scattering and Velocity – field curves
Low-field: Mobility
High field – Velocity Saturation, Optical Phonon emission

9. Table of Scattering Processes

10. Theoretical Formalism

11. Theoretical Formalism – Contd…

12. Theoretical Formalism – Contd…

13. Theoretical Formalism – Contd…
FERMI’S GOLDEN RULE

14. Transport in a Silicon MOSFET
Electron Distribution in k-space
Electron Distribution in Real-Space

15. Ballistic Transport – Electrons as waves
Electrons flow and “diffract” like
Waves on surface of water…

16. Optical Properties

17. Light in periodic structures…
Photonic Bandgap Crystals

18. Bandgaps for light…

19. Quantum Confined Structures

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

21. Bulk Semiconductor – Device Applications
Today’s HBT
The First Transistor (1947)
Today’s MOSFET

22. Quantum – Well Devices GaN HEMTs High-electron Mobility Transistors
GaAs Laser Diodes

23. Quantum Well Devices – GaN Solid State Lighting
Blu-Ray DVD (GaN QW Laser)
White LEDs -
The New Bulbs!

24. Superlattices – Device Applications
Quantum Cascade Lasers

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

26. Quantum Wire Device Applications
Nanowire Laser Arrays
Nanotube FETs

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

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

29. And Finally… The NEW Christmas Lights!
Hope you take away from this class the
Excitement of this field …