(a) Using the data presented in Figure 18.16, determine the number of free electrons per a...

(a) Using the data presented in Figure 18.16, determine the number of free electrons per atom for intrinsic germanium and silicon at room temperature (298 K). The densities for Ge and Si are 5.32 and 2.33 g/cm3, respectively.

(b) Now, explain the difference in these freeelectron-per-atom values.

Figure 18.16 Intrinsic carrier concentration (logarithmic scale) as a function of temperature for germanium and silicon.

(From C. D. Thurmond, “The Standard Thermodynamic Functions for the Formation of Electrons and Holes in Ge, Si, GaAs, and GaP,” Journal of the Electrochemical Society, 122, [8], 1139 (1975). Reprinted by permission of The Electrochemical Society, Inc.)