Ionization energy Bohr model Ionization energy Bohr model
Ionization energy – Bohr model + -
Ionization energy – Bohr model
Ionization energy – Bohr model
Fermi-Dirac distribution
Distribution of states & electrons Fermi function. .
Figure 3 -1 a
Figure 3 -1 a
Problem 3. 5 The magnitude of the product g(E) & Fermi(E) in the conduction band is a function of energy as shown in Figure 3. 1. Assume the Boltzmann approximation is valid. Determine the energy with respect to Ec at which the maximum occurs.
Problem 3. 5
Problem 3. 5
Typical numbers Normalized electron Normalized hole effective mass Silicon 1. 08 0. 56 Gallium arsenide 0. 067 0. 48 Germanium 0. 55 0. 37 Normalized mass equals effective mass/rest mass of the electron
n type extrinsic semiconductor
p type extrinsic semiconductor
Ionization energies in silicon and germanium in electron volts Impurity Donors Phosphorus Arsenic Si Ge 0. 045 0. 0127 0. 045 0. 06 0. 0104 0. 0102 Acceptors Boron Aluminum
Conduction band Valence band
Current density – charges in motion - +
collisions +
collisions +
collisions +
Lattice structure will also vibrate due to T > 0 “lattice scattering”
Conductivity and resistivity
Conductivity and resistivity V I
You enter the laboratory and see an experiment. How will you know which class is it? If it's green and wiggles, it's biology. If it stinks, it's chemistry. If it doesn't work, it's physics.
Teachers' remarks that changed the history of physics Copernicus, when will you understand that you are not the center of the world? Galileo, if you will drop stones from the top of the tower one more time, you will be dismissed forever. Kepler, till when will you stare at the sky? Newton, will you please stop idling away under the apple tree? Ohm, must you resist Ampere's opinions on current events? Nikola Tesla, I see that everyone is attracted to your magnetic personality. Einstein, a crocodile is greener or is it wider? Schrödinger, stop abusing cats! Heisenberg, when will you be sure of yourself?
Simple three-dimensional unit cell
- Slides: 28