ECE331_Wi06_hw5_sol

# ECE331_Wi06_hw5_sol - ECE331 Homework#5 Solution(Due Monday...

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1 ECE331 Homework #5 Solution (Due Monday, February 20, 2006) 1. Streetman 3.1. From eq.3.8 and Appendix II we have eV J h q m E r n 052 . 0 10 34 . 8 ) 10 63 . 6 ( ) 2 . 13 10 85 . 8 ( 8 ) 10 6 . 1 ( 10 11 . 9 ( 067 . 0 ) ( 8 22 2 34 2 12 4 19 ) 31 2 2 0 4 * = × = × × × × × = = ε Thus the energy required to excite the donor electron from the n=1 state to the free state (n= ) is about 5.2 meV. 2. Streetman, 3.2

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2 3. Streetman, 3.3 Since an unknown material is doped with 10 15 cm -3 donors, the concentration of electron in the conduction band is 3 15 0 10 = = cm N N N n d a d Since the Fermi level lies at least several kT, the concentration of electron in the conduction band is 3 5 0 10 4 . 6 0259 . 0 ) 25 . 0 ( exp ) ( exp × = = = cm N eV eV N kT E E N n C C F C C Thus 3 5 3 15 10 4 . 6 10 × = cm N cm C V C N cm N = × = 3 19 10 56 . 1 3 9 19 10 36 . 9 0259 . 0 2 ) 1 . 1 ( exp 10 56 . 1 2 exp × = × × = = cm eV eV kT E N N n g V C i The concentration of holes is 3 4 15 2 9 0 2 0 10 7 . 8 10 / ) 10 36 . 9 ( / × = × = = cm n n p i 4. Streetman 3.7.
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ECE331_Wi06_hw5_sol - ECE331 Homework#5 Solution(Due Monday...

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