Please explain me. I don't understand what is quasi fermi level f(E) and fermi energy E(adsbygoogle = window.adsbygoogle || []).push({}); _{f}.

For example (GaAs) at the room temperature (T=300K)

E_{g}= 1.42 eV; (energy band gap)

m_{c}= 0.067 m_{e}; (effective mass of electron in conduction band)

m_{v}= 0.45 m_{e}; (effective mass of hole in valance band)

kT = 0.0259; (T=300K)

For intrinsic fermi Energy from the middle band gap can receive

using this equation

E_{i}= 3kT/4*ln(m_{v}/m_{c});

E_{i}= 0.0369 eV; (intrinsic fermi Energy from the middle band gap)

Engery band gap E_{g}is 1.42 eV so middle band gap is 1.42/2 = 0.71 eV;

So intrinsic fermi Energy is

0.71 eV+0.0369 eV = 0.7469 eV.

Now i calculate for fermi level

using this equation

f(E) = 1/(exp(E-E_{f}/kT)+1);

E is the E_{g}? I calculate where E is value of E_{g}.

received

f(E) = 4.925 x 10^{-12};

This is right?

And then i understand that only one fermi level in intrinsic semiconductor at the thermal equilibrium, no bias (voltage, EM radiation, light). When semiconductor is under bias, may be quasi fermi level(2 levels) in intrinsic semiconductor or this happen only in extrinsic semiconductor? Please explain me with above example.

I need your help.

Thanks a lot

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# I Quasi Fermi level and intrinsic Fermi energy

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