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Unformatted text preview: Name: U _____ EE138: Quiz #4 U Note: The quiz is closed book and closed note. With the exception of your calculator, the use of all electronic devices is prohibited. Please write your answers clearly. You have 15 minutes. A sample of silicon is doped with indium for which the electron acceptor level (EA) is 160 meV above the top of the valence band. (a) Is this semiconductor material doped n‐type, p‐type, or intrinsic? (5 pts.) (b) What is the majority carrier in this semiconductor? (5 pts.) (c) Sketch the band diagram for this material. Clearly label the conduction band edge, valence band edge, and the acceptor level (EA). (10 pts.) (d) Write a general equation describing the charge neutrality condition in this semiconductor. (10 pts.) (e) What impurity density (NA) would cause the Fermi level (EF) to coincide with the acceptor level (EA) at 300 K? me* = 0.58mo and mh* = 0.39mo where mo is the mass of the free electron. Assume Ne is negligible. (60 pts.) (f) What fraction of the acceptor levels is filled in (d)? (10 pts.) ...
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