Electric field between bands in semiconductors

[green-fresh]

i read in an online course about semiconductors that electric field between E_c and E_v
given by:

E=\frac{dE_c}{q dx}

and i know the general form of electric field is :
E=\frac{k.q_0.q}{r^2}
and what is the direction of this field ,i know from positive to negative , from E_c to E_v? because both E_c & E_c have electrons and holes

and dose anyone know what is \mu_n electron mobilities

thank you very much!

 

[uart]

First off be careful with your notation. When using Electric Field and Energy you're best off not to use the symbol "E" for both. Consider using "E" for electric field and "W" for work or energy.

Second and more important, you seem to have a fundamental misunderstanding of the semiconductor energy band model. The conduction and valence bands represent different energy levels in the semiconductor, they are not spatially separated.

 

[green-fresh]

yes! I'm sorry you are right
could i have an electric field between negative charge and positive charge even if there isn't a space between them .
and is it correct that:
the direction of this field is,i know from positive to negative , from CB(conduction band) to VB ?