N(E): Density of states

f(E): Probability that a quantum state with energy E is occupied by an electron

Ec : Energy level of the conduction band

The expression \(\mathop \smallint \limits_{{E_c}}^\infty N\left( E \right)f\left( E \right)dE\) gives

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  1. minimum number of electrons in conduction band
  2. concentration of electrons in conduction band
  3. energy of electron concentration in conduction band
  4. conductivity of electrons in conduction band

Answer (Detailed Solution Below)

Option 2 : concentration of electrons in conduction band
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The given expression:

\(\mathop \smallint \limits_{{E_c}}^\infty N\left( E \right)f\left( E \right)dE\)

N(E) gives the distribution of allowed states for electrons over energy.

f(E) gives the fraction of the total allowed states being occupied by an electron.

\(∴ \mathop \smallint \limits_{{E_c}}^{E_T} N\left( E \right)f\left( E \right)dE\) gives the concentration of electrons from energy Ec to ET.

Where Ec denotes the bottom of the conduction band and ET denotes the top of the conduction band.

For simplicity, we can replace ET with infinity.

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