hw6_1102

# hw6_1102 - voltmeter with copper leads to contacts on...

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EECE7201 H.W. #6, Due March 15, 2011 1. 5.1, text. 2. 5.2, text. 3. A silicon step junction N A = 4X10 18 cm -3 (assume non-degenerate), N D = 10 16 cm -3 , is at 300K. Calculate the following in equilibrium, assuming the depletion approximation. a. V bi b. x n , x p , and W c. n po and p no d. Percentage of the depletion region on the p-side 4. A silicon step junction N A = 4X10 18 cm -3 (assume non-degenerate), N D = 10 16 cm -3 , is at 300K. (Same as problem 3) a. Determine the junction capacitance for an applied voltage of 0 V. b. Determine the saturation current, assuming tn = tp = 10 -6 sec. c. Recompute a. and b. for a change in N A to 4X10 17 . d. Recompute a. and b. for a change in N D to 10 15 , keeping N A at 4X10 18 . e. Which change has a larger effect on the characteristics? 5. An attempt to measure the internal contact potential of a p-n junction is made by connecting a
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Unformatted text preview: voltmeter with copper leads to contacts on opposite sides of the junction. The voltmeter reads zero. Explain the failure of this method. 6. Derive the I-V characteristics of the short-base diode shown, where the boundary condition at the contact on the n-side is given by Sp very large (equivalent to saying that the excess minority carrier concentration is zero). Note that this is not in either limit discussed in the text! You need to do the diffusion problem including both positive and negative exponentials. x n ' - x n is on the order of L p , x p ' - x p >> L n . L p and L n are the minority carrier diffusion lengths....
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