a) Sketch the variation of electron concentration with temperature for
i) an n-type semiconductor doped with 1021 donors m-3
ii) an intrinsic semiconductor.
b) Explain briefly why the intrinsic carrier concentration at a given temperature is greater for germanium than for silicon.
c) At a temperature of 293 K an intrinsic semiconductor has an electron mobility of 0.12 m2V-1s-1 and a hole mobility of 0.07 m2V-1s-1.
If its resistivity is 35 :m, calculate the intrinsic carrier concentration. Hence calculate the hole concentration when the semiconductor is doped with 1021 donors m-3.
d) If a voltage of 0.5 V is applied across the opposite faces of a sample of the above intrinsic semiconductor (in part c) of thickness 0.2 mm, determine the approximate total current density and the average drift velocity of the holes.