ECE_536__Problem_Set_1 - a donor or an acceptor E D and E A...

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ECE 536 Problem Set 1 Due Monday Sept. 29 1. Assuming dopant atoms are universally distributed in a silicon crystal, how far apart are these atoms when the doping concentration is (a) 10 15 cm -3 (b) 5x10 20 cm -3 2. Estimate the resistivity of pure silicon in ohm-cm at (a) room temperature (b) 77K, and (c) 1000C. Neglect the temperature dependence of the carrier mobility in making this estimate 3. (a) Show that the minimum conductivity of a semiconductor sample occurs when (b) What is the expression for minimum conductivity? (c) Is value greatly different than the value calculated in problem 2? 4. When an Au atom sits on a lattice site in a silicon crystal, it can act as either
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Unformatted text preview: a donor or an acceptor. E D and E A levels both exist for the Au and both are close to the middle of the silicon bandgap. If a small concentration of Au is placed in an N-type silicon crystal, will the Au behave as a donor or acceptor? Explain 5. A silicon diode has doping concentrations on the N and P sides of N D =1x10 19 cm-3 and of N A =1x10 15 cm-3 . Calculate the process temperature at which the two sides of the diode becomes intrinsic. 6. A piece if N-type Silicon has a donor level E D =.01eV. Assuming there are no other impurities in the crystal, what is the position of the Fermi level at absolute zero?...
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ECE_536__Problem_Set_1 - a donor or an acceptor E D and E A...

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