# How to understand effect of increase in band gap generated away from Fermi energy on conductivity?

An example would be that when we dope Nitrogen in graphene its conductivity decreases. This can be explained through other means. But can this be explained through the change in its band structure?

• What does "generated away from Fermi energy" mean here? – Kevin J. M. Nov 29 '20 at 2:12

$$\sigma = \frac{ne^2\tau}{m^*}$$
you can think of the band structure providing the effective mass $$m^*$$, but not the relaxation time $$\tau$$ in between scattering events. This scattering time can be strongly affected by doping or other imperfections in the crystal.