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Phys 460 Lecture 21
(
pdf version - 6 slides/page
)
Wednesday, November 8, 2006
Lecturers: R. Martin and Prof. M. Nayfeh
No new homework today
Reading:
Kittel, ch. 18, added material
Added Slides for presentation by M. Nayfeh
Semiconductor Nanostructures
Outline
From previous lectures:
Part I: Crystal Structures, Diffraction, Reciprocal Lattice, Crystal binding
Phonons, Dispersion curves, Thermal properties
Part II: Free electron gas, Energy bands for electrons in crystals E
k
n
, gaps, metals vs. insulators
Semiconductors
Effective mass, negative electrons and positive holes, doping
Semiconductor devices - inhomogeneous semiconductors
Variations of band energies, p-n junctions
Rectification; Light-emitting diodes; Solar cells
Bipolar Transistor n-p-n p-n-p
Semiconductor structures
Control semiconductor properties by voltages or material growth
Heterostructure formed of different semiconductor materials
Today: Semiconductor nanostructures
Structures that confine electrons
"Electron in a box" - confined in all directions
How small do structures need to be to exhibit quantum size effects
Estimate in terms of the effective mass
Typical energies
Experimentally made systems have important effects
Special addition - Presentation by Prof. M. Nayfeh
Si nanoclusters - as small as Si29H36
Strong dependence on size - Very large changes in the gap compared to bulk Si
Typical energies
Absorption and emission of light - demonstration
Use in biological applications
Email clarification questions and corrections to
rmartin@uiuc.edu
Email questions on solving problems to
xin2@.uiuc.edu