Question

We have seen in class that at low temperatures, not all dopants are ionized. Consider a Si sample doped with 10^17 cm-3 donors with the location of the donor level ED in the Si bandgap given by EC − ED = 50 meV . Calculate the temperature at which only 50% of the donors are ionized. Assume NC = NV = 2×10^19 cm^-3 and independent of temperature.

(b) For the same sample, calculate the high temperature limit of the extrinsic range as defined by the temperature at which the donor density equals ni. Note that ni is a strong function of temperature.

Answer 1