For the following 4 semiconductors calculate the parameters listed in the table.

Question

For the following 4 semiconductors calculate the parameters listed in the table. The semiconductor is Si at room temperature. For simplicity, assume the intrinsic Fermi level to be located at the middle of the band gap.

Note: For Intrinsic Silicone ni = 1.0 x 10^10 Eg = 1.10 eV

Doping Concentration Fermi level With respect
to Intrinsic Fermi level
(Ef - Ei) eV Fermi Level with respect
to conduction band
(Ec - Ef) eV Fermi Level
with respect to valence band
(Ef - Ev) eV Electron
Concentration
(n) cm-3 Hole
concentra-
tion
(p) cm-3 39

Explanation / Answer

N = Ni*exp[-(E-Ei)/KT]

a) N =39*10^14 cm^-3 As (donor) N>Ni

k*T =4.11*10^-21 J = 0.0256 eV

(E-Ei)/KT = 12.87

E-Ei =0.329 eV the level is above Ef with 0.329 eV

Ec-E = Eg/2 -(E-Ei) = (1.1)/2 -0.329 =0.22 eV the level is below Ec with 0.22 eV

E-Ev = Eg/2 +0.329 =0.897 eV level above Ev with 0.897 eV

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