ECE230A_Homework-4

ECE230A_Homework-4 - ECE230A Homework due: December1, 2009...

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ECE230A Homework #4 Homework due: December1, 2009 1. In class, we derive the expression of mobility from the Boltzman transport equation and find ߤൌ כ ۃఛ௩ ۄ ۃ௩ ۄ where τ is the relaxation time. Derive (a) Derive the expression of diffusivity D from the Boltzman transport equation. (b) Show that for non-degenerate semiconductors, the Einstein relation ௞் is satisfied. (c) Explain why the results of mobility and diffusivity only work under low field condition. 2. When we derived the continuity equation for the excess carriers, we strated from the following continuity equations of total electron and hole populations: డ௡ డ௧ ൌߤ డሺ௡ா డ௫ ൅ܦ డ௫ ௡ି௡ (1) డ௣ డ௧ ൌെߤ డሺ௣ா డ௫ ൅ܦ డ௫ ௣ି௣ (2) (a) Complete the derivation to achieve the final result: డ௡ డ௧ ൌܦ
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This note was uploaded on 10/09/2010 for the course ECE 230 at UCSD.

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ECE230A_Homework-4 - ECE230A Homework due: December1, 2009...

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