I am trying to find the amount of electrons in a conduction band in Si (Silicon), all I've got is a graph similar to this one:
I've tried to integrate like this: $$ N = \int_{1}^{\infty} \frac{1}{1+\exp(E-E_f)} \cdot D(E)\text d E$$
However, I have a hard time finding what $D(E)$ is supposed to be. If i put is as: $D(E) = C \cdot \sqrt{E}$, where $C = \text{const.}$ The integral becomes unsolvable.
I appreciate any help!