Consider an n-type semiconductor with a band gap of 0.8 eV, and with 1021 dopant atoms per m3, giving 2 × 1021 donor levels per m3, which are 0.04 eV below the conduction band.
(a) At absolute zero, is the Fermi level above, below, or at the donor levels?
(b) At what temperature is the Fermi level 0.08 eV below the donor level?
(c) At 300 K, how many conduction electrons come from donor levels? From the valence band?
(d) Above what temperature will this semiconductor become intrinsic?