MidtermSolutions230

MidtermSolutions230 - Name: Student ID: ECE230A Midterm -1...

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Unformatted text preview: Name: Student ID: ECE230A Midterm -1 ALLOWED: Open book, note, and homeworks. Scientific or programmable calculators. NOT ALLOWED: Laptop computers, internet/e-mail access, discussions. 1. (30 pts) Consider a two-level system at thermal equilibrium. The concentration of particles N = 10 18 cm-3 . There are 10 19 cm-3 states at each energy level. (a) (10 pts) Assuming E 2 =1.1eV, E 1 =1.0 eV, T= 300K, find N 1 and N 2 if the system obeys Boltzman statistics. ( k B T = 0.026 eV). N 1 and N 2 are the carrier concentrations at each level. According to Boltzman Statistics ? ~ ? / ? ? 1 ? 2 = ? 1 / ? ? 2 / ? ? 1 ? 2 = ? ( 1 2 )/ ? ? 1 = ? 2 ? ( 1 2 )/ ? (1) ? = ? 1 + ? 2 (2) Using (1) and the given values we get 10 18 = ? 2 ( ? .1 0.026 + 1) ? 2 = 2.09 10 16 ? 3 ? 1 = 9.8 10 17 ?...
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MidtermSolutions230 - Name: Student ID: ECE230A Midterm -1...

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