Engineering Materials Week 13 Interacti

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Engineering Materials Week 13-Interactivity
18.3 Which of ZnS and CdSe will have the larger band gap energy Eg. Cite reason(s) for your choice.
Zinc sulfide will have a larger band gap energy than cadmium selenide. Both are II-VI compounds, and Zn and S are both higher vertically in the periodic table than Cd and Se. In moving from bottom to top up the periodic table, Eg increases.
18.6 On the basis of Figure 18.17, as dopant level is increased would you expect the temperature at which a semiconductor becomes intrinsic to increase, to remain essentially the same, or to decrease? Why?
As dopant level is increased the point at which the intrinsic region becomes dominant moves horizontally to higher temperatures.
18.8 Would you expect increasing temperature to influence the operation of p-n junction rectifiers and transistors? Explain.
If the temperature of a p-n junction rectifier or a junction transistor is raised high enough, the semiconducting materials will become intrinsic and the device will become inoperative.
18.9 For solid lead titanate (PbTiO₃) what kind(s) of polarization is (are) possible? Why?
Electronic, ionic, and orientation polarizations would be observed in lead titanate. Electronic polarization occurs in all dielectric materials. The lead, titanium, and oxygen would be ionic in character. Orientation polarization is also possible inasmuch as permanent dipole moments may be induced

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