Pn junction, diode and energy level of conduction band during forward biasing

[fisico30]

Hello Forum,

I am looking at the energy levels between the n and p regions of a diode. The p-side has a conduction band that starts at a higher energy (same for the valence band).
The n-side has the valence and condution bands that are at lower energy.

The Fermi energy line is the same for both...

I don't understand what happens to the energy level of the conduction band when the diode is forward biased...
does the conduction band of the p side gets lower and the conduction band of the n-side gets higher? Why? Do they need to match?

thanks
fisico30

 

[fisico30]

I guess I am talking about the energy gradient that an electron in the n-side needs to climb...

Does forward biasing reduce that energy difference? Why does that energy difference exist?

Again, The valence band and conduction band in N-Type material are slightly lower than that of P-Type material.

 

[fisico30]

Or is the tension on the string that plays the role of the centripetal force?