Solid state CB Flashcards
1/tau
probability of collision per unit time
Hall effect
when a B-field is applied to a conductor - the resulting Lorentz force balances out the “Hall field”
Relaxation time approximation
On average electrons are scattered after a time tau, which is not a function of k
Effective mass
band structure inertia
Elastic scattering
no change in energy, from static crystal defects
Inelastic scattering
change in energy, from absorption/emission of phonons
Phonon
lattice excitation (standing wave)
Semiconductor
an insulator for which we have control over the number of mobile carriers, which affects the conductivity
Direct/indirect band gap
HOMO and LUMO at same/different k vector
Intrinsic semiconductor
carrier density dominated by intrinsic carriers thermally excited from the VB to the CB
Degenerate
high doping levels, Fermi-Dirac statistics important (like a metal)
Non-degenerate
low doping levels, multiple occupancy unlikely
Extrinsic semiconductor
carrier density dominated by e- or h+ from impurities
Mobility
the measure of how quickly e- or h+ respond to an applied electric field
Compensation
adding minority dopants results in the sum (n+p) decreasing
