How does a work function difference cause band bending in equilibrium in Metal-Oxide-Semiconductor (MOS)? I don't understand the physical meaning behind this sentence from Sze:
to accommodate the work function difference, the semiconductor bands bend
I understand that the work functions are the the energies required to move an electron from the fermilevel to the vacuum. I do not understand why this implies band bending when a metal and a semiconductor of different work functions are brought together.