513.001 Molecular and Solid State Physics
Exam November 2009
The effective densities of states for several semiconductors are given below.
What is the chemical potential energy for intrinsic Ge measured from the top of the valence band at 300 K?
Germanium is doped with acceptor atoms to a density of 4×1017 cm-3. What is the chemical potential of the doped material measured from the top of the valence band at 300 K?
Germanium is an indirect semiconductor and has an fcc Bravais lattice. The valence band maximum is at k = 0 but the conduction band minimum is in the <111> direction. Draw the dispersion relation (energy vs. k) for energies near the top of the valence band and bottom of the conduction band. Energy should be measured in electron volts in the drawing.