Expression for electrical conductivity in intrinsic semiconductor
The general expression for the electrical conductivity, σ = neμ
The intrinsic electrical conductivity, σi = [neμe + peμh]
But n = p = ni
Therefore σi = [nieμe + nieμh]
σi = nie [μe + μh]
where, μe electron mobility and μh hole mobility
\sigma_i=\left(\mu_e+\mu_h\right) e \cdot 2\left(\frac{2 \pi K T}{h^2}\right)^{\frac{3}{2}}\left(m_e^* m_h^*\right)^{\frac{3}{4}} \exp \left[\frac{-\left(E_g\right)}{2 K T}\right]The electrical conductivity depends on the negative exponential of and the mobilities μe and μh . But the [μe + μh] is found to be proportional to T -3/2 . So that we can neglect [μe + μh] .
The Electrical conductivity
eqn(1)
\sigma_{\mathrm{i}}=\mathrm{Cexp}\left[-\frac{\mathrm{E}_{\mathrm{g}}}{2 \mathrm{KT}}\right]where, C is a constant.
Taking log on both sides of equation (1),
Fig (1)
From the graph, we know that the electrical conductivity increases when temperature increases.
| Read More Topics |
| Mobility and conductivity in semiconductors |
| Elemental and compound semiconductor |
| Types of semiconductors |
