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# Homework%2007 - EEE 352-Spring 2008 Homework 7 4.18 The...

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EEE 352—Spring 2008 Homework 7 4.18 The electron concentration in silicon at T = 300 K is n 0 = 5 × 10 4 cm -3 . (a) Determine p 0 . Is this n-type or p-type material? (b) Determine the position of the Fermi level with respect to the intrinsic Fermi level. (a) Using (4.43), we have 3 15 4 2 10 0 2 0 10 5 . 4 10 5 ) 10 5 . 1 ( × = × × = = cm n n p i . This is p -type material. (b) Using (4.65), we have eV p n T k n n T k E E i B i B Fi F 327 . 0 ln ln 0 0 = = = . 4.19 Determine the values of n 0 and p 0 for silicon at T = 300 K if the Fermi energy is 0.22 eV above the valence band energy. The energy of 0.22 is far above the acceptor level, so that we can assume that all the acceptors are ionized. Hence, we can use the simple formulae: 3 5 15 2 10 0 2 0 3 15 19 0 10 06 . 1 10 13 . 2 ) 10 5 . 1 ( 10 13 . 2 0259 . 0 22 . 0 exp 10 04 . 1 exp × = × × = = × = × = = cm

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Homework%2007 - EEE 352-Spring 2008 Homework 7 4.18 The...

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