hw10 - W vs. N d for the junctions described in (a). (d)...

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ECE 440 Homework X Spring 2006 Due: Wednesday, March 15, 2006 1. A n + -p Si junction with a long p-region has the following properties: N a =2x10 16 /cm 3 ; μ n = 1000 cm 2 /V-s; μ p = 360 cm 2 /V-s; τ n =1 μs. If we apply 0.75 V forward bias to the junction at 300 K, what is the electric field in the p-region far from the junction? Draw a band diagram in the p-region far from the junction assuming that the junction is at x=0 and the p-side is in x>0. 2. Consider the following Si p-n junctions operating at 300 K. (a) Using Eq. (5-8), calculate the contact potential V o for N a = 1x10 15 and 1x10 18 /cm 3 , with N d = 10 15 , 10 17 , 10 19 /cm 3 in each case and plot V o vs. N d . (b) Plot the maximum electric field E o vs. N d for the junctions described in (a). (c) Plot the width of the depletion region
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Unformatted text preview: W vs. N d for the junctions described in (a). (d) Given that N a = 10 15 (and repeat for 10 18 /cm 3 ) and N d = 10 19 /cm 3 , determine the reverse bias needed to yield a maximum electric field E o in the junction which exceeds 5x10 5 V/cm. 3. A p +-n silicon diode (V o = 0.926 volts) has a donor doping of 10 17 /cm 3 and an n-region width = 1 m. Assume that the diode has a uniform cross sectional area of 0.001 cm 2 . Refer to Fig. 5-22 for the following questions. (a) Does it break down by avalanche or punchthrough? Determine the depletion capacitance when the breakdown happens. (b) If the doping is only 1x10 16 /cm 3 , what is the minimum n-region width for punchthrough not to take place?...
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