And gaas and alp the data table

7	Composition (at% Zn)					Questions and Problems
	Composition (at% Zn)					FIGURE 12.35 Room-temperature
		10	20	30		FIGURE 12.35 Room-temperature
		10	20	30

						alloys. (Adapted from Metals
6						Handbook: Properties and


5
5
4						1979, p. 315.)
3
2
1
0
0	0	10	20	30	40

	are 1.5 free electrons per gold atom. The electrical conductivity and density for Au
	are 4.3 � 107(�-m)�1and 19.32 g/cm3, re-	this alloy given the following data:
	spectively. (b) Now compute the electron	this alloy given the following data:
	spectively. (b) Now compute the electron	Electrical
12.15
	From Figure 12.35, estimate the value of A in Equation 12.11 for zinc as an impurity
		Phase			Density *(g/cm3)*
12.16	in copper–zinc alloys.	�		1.88 � 10�8		8.94
12.16	(a) Using the data in Figure 12.8, determine	�		5.32 � 10�7		8.25
	the values of �0 and a from Equation 12.10 for pure copper. Take the temperature T	12.19	The room-temperature electrical resistivit-ies of pure lead and pure tin are 2.06 �
		12.19

		composition for all compositions between
	Figure 12.8. (c) Using the results of parts a and b, estimate the electrical resistivity of	composition for all compositions between
		pure lead and pure tin.
		pure lead and pure tin.
12.17
	Determine the electrical conductivity of a
	Cu-Ni alloy that has a yield strength of 125
	Cu-Ni alloy that has a yield strength of 125
	MPa (18,000 psi). You will find Figure
12.18		(c) Explain the shapes of these two curves, as well as any differences between them.
	Tin bronze has a composition of 92 wt% Cu and 8 wt% Sn, and consists of two phases
		12.20 A cylindrical metal wire 2 mm (0.08 in.) in diameter is required to carry a current of 10 A with a minimum of 0.03 V drop per
	at room temperature: an � phase, which is copper containing a very small amount of
	tin in solid solution, and an � phase, which

396	●		12.27

	candidates?
12.21	(a) Compute the number of free electrons and holes that exist in intrinsic germanium		12.28
				tion involving an acceptor impurity atom.
				tion involving an acceptor impurity atom.


				sume that the impurity elements are substi-
	for Ge and Si, which are 5.32 and 2.33 g/ cm3, respectively.

12.22
				N	Si
				B	Ge
	ature as follows: n, p � exp��Eg 2kT�	(12.38)		B	Ge
				Zn	GaAs
				S	InSb
				In	CdS
				In	CdS
				As	ZnTe
	or, taking natural logarithms,		12.29
			12.29
12.23			12.30

	Thus, a plot of the intrinsic ln n (or ln p)
				tor? (c) Make a schematic plot of Fermi energy versus temperature for an n-type
				semiconductor up to a temperature at


	trinsic, compound, elemental. Now provide an example of each.			(a) The room-temperature electrical con-ductivity of a silicon specimen is 103(�-
12.24			12.31

				hole mobilities for silicon in Table 12.2,
12.25	your answer.			hole mobilities for silicon in Table 12.2,
	your answer.
	For each of the following pairs of semicon-
	ductors, decide which will have the smaller
	ductors, decide which will have the smaller

				Using the data in Table 12.2, compute the electron and hole concentrations for intrin-
12.26			12.32	sic InSb at room temperature.
				sic InSb at room temperature.

	free electrons in numbers in excess of those
				ductor at room temperature, and virtually all the Sb atoms may be thought of as being
				ionized (i.e., one charge carrier exists for each Sb atom). (a) Is this material n-type or p-type? (b) Calculate the electrical con-

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