Using n=Nce−(Ec−μ)/kBT, derive a formula for how far μ shifts, relative to its position in the pure crystal, when a crystal's electron density is raised from the intrinsic value ni to a doped value n. Then use it to find that shift for silicon doped so that n=1.0×1015cm−3, with ni=1.0×1010cm−3 (the measured value), and check the result against the chapter's own doped worked example.