Understanding Band Bending at Metal-Semiconductor Junctions

[Excom]

Hi everyone.

Is there anyone that can explane the band bending, whiche takes plane when a metal and a semiconductor are joined together?

In illustrations of the band bending, it looks like that the energy of the valence and conduction band far from the junction have been lowered or raised. Is that true? And if yes, how can that be true? I mean, the electrons far from the junction, they are probably not affected by the junction.

 

[Defennder]

If there is a difference in the Fermi levels of the respective materials (metal and semiconductor), and there usually is, then electrons/holes will flow from one to the other until thermal equilibrium is obtained. Depending on the relative workfunction differences of the metal and semiconductor, an ohmic or Schottky contact will be formed. And it doesn't appear that the energy of Ec and Ev have been raised or lowered. chi (energy difference between Evac and Ec remains the same for semiconductor bulk far from the contact point)

 

[Excom]

Okay, thanks.