University of California, Riverside

EE 13599

how all work for full credit. Use values from graphs in lecture notes as needed.
1. (5pts) At room temperature, which semiconductor has the largest intrinsic carrier concentration? Explain.
(a) Si (EG = 1.1 eV) (b) Ge (EG = 0.7 eV) (c) GaAs (EG = 1.4 eV)
2. (5pts) At room temperature, which semiconductor has the highest electron mobility? Explain.
(a) Si (ND = 1014 / cm3) (b) Si (ND = 1017 / cm3) (c) Both (a) and (b) have same mobility.
3. (5pts) In problem 2, which semiconductor has the highest conductivity? Explain.
4. (15pts) At any temperature, the mobility of n-type GaAs is higher than that of n-type Si. Make a back of the
envelope estimate of the ratio of the two mobilities, and compare the value to the actual ratio from the graphs
in the lecture notes at T = 300K. Use values for the effective masses given here