Ge is doped with phosphorous, an n$-$type impurity, that produces an donor energy level,

Ed$,$ located $0\mathrm{.}012$ eV below the conduction band edge, Ec$.$ The bandgap energy, Eg$,$ for Ge

is $0\mathrm{.}68$ eV and its Fermi level, Ef$,$ is located $0\mathrm{.}2$ eV above its intrinsic level for the doping

level present. Assume the temperature is $300$ K$.$