1A ,One charge transport mechanism in a semiconductor is carrier drift, which is the flow of carriers due to an applied electric field,
B, Carriers reach an average drift velocity due to scattering events in a semiconductor with an applied electric field. Two scattering events within a semiconductor are lattice scattering and ionized impurity scattering.
C, The average drift velocity is a linear function of the applied electric field for small values of electric field, but the drift velocity reaches a saturation limit that is on the order of 10七次方cm/s for electric fields on the order of 10四次方V/cm.
D,Carrier mobility is the ratio of the average drift velocity to the applied electric field. The electron and hole mobilities are functions of temperature and of the ionized impurity concentration.
E, The drift current density is the product of conductivity and electric field(a form of Ohm's law). Conductivity is a function of the carrier concentrations and mobilities.Resistivity is the inverse of conductivity.
2,A , The second charge transport mechanism in a semiconductor is carrier diffusion, which is the flow of charge due to a gradient in carrier concentration.
B, The diffusion current density is proportional to the diffusion coefficient and the gradient in carrier concentration.
3,A, An electric field is induced in a semiconductor in thermal equilibrium that has a nonuniform impurity doping concentration.
B, The diffusion oefficient and mobility are related through the Einstein relation.
4, A, Generation is the process whereby electrons and holes are created; recombination is the process whereby electrons and holes are annihilated.
B, Generation and recombination rates were defined for thermal equilibrium and for nonequilibrium excess carriers.
C, Excess minority-carrier lifetimes were discussed and defined.
5, The Hall effect is a consequence of a charged carrier moving in the presence of perpendicular electric and magnetic fields. The chargeed carrier is deflected, inducing a Hall voltage. The polarity of the Hall voltage is a function of the semiconductor conductivity type. The majority-carrier concentration and mobility can be determined from the Hall volrage.