# hw9 - (a Using mobility values from Fig 3-23(better yet the...

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ECE 440 Homework IX Fall 2005 Due: Monday, October 17, 2005 1. An abrupt Si p-n junction has the following properties at 300 K: p-side n - s i d e A = 1 0 -3 cm 2 N a = 2x10 17 /cm 3 N d = 4x10 15 /cm 3 τ n = 0.1 μs τ p = 10 μs μ p = 190 cm 2 / V - s μ n = 1200 cm 2 /V-s μ n = 600 cm 2 / V - s μ p = 420 cm 2 /V-s (a) Draw the band diagram qualitatively under forward and reverse bias showing the quasi-Fermi levels. (b) Calculate the reverse saturation current due to holes, due to electrons and the total reverse saturation current. (c) Calculate the total injected minority carrier current for V = V o /3 and V o /2. (d) Assuming μ’s and τ ’s do not change with temperature, repeat part (c) for a temperature of T = 400 K at which the intrinsic carrier concentration n i = 6x10 12 /cm 3 . 2. Assume that an abrupt Si p-n junction with area 10 -4 cm 2 has N a = 8x10 16 /cm 3 on the p-side and N d = 2x10 17 /cm 3 on the n side. The diode has a forward bias 0.6 volts.
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Unformatted text preview: (a) Using mobility values from Fig. 3-23 (better yet the information sheet) and assuming that τ n = τ p =1 μs, plot I p and I n versus distance on a diagram such as Fig. 5-17, including both sides of the junction. Neglect recombination within the space charge region, W. (b) Plot δ n(x p ) and δ p(x n ). (c) Determine the separation of quasi-Fermi levels at the position 2 μm into the quasi neutral region in both sides of the junction. 3. A p +-n Si junction with a long n-region has the following properties: N d =2x10 16 /cm 3 ; D n = 25 cm 2 /s; μ p = 360 cm 2 /V-s; τ p =1 μs. If we apply 0.7 V forward bias to the junction at 300 K, what is the electric field in the n-region far from the junction?...
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