Question

Why is there a difference between Fermi levels in metals and metal-oxide semiconductors (MOS)?

Answer 1

Hey mate ^_^

When there is a potential difference between two thermodynamic systems, of which each is in equilibrium (here the gate and the semiconductor bulk), the chemical potentials (Fermi levels) of these systems will differ by qV

#Be Brainly❤️

Answer 2

The metal gate and the semiconductor, separated by an insulator in the MOS structure, can be each be considered to be a system in thermodynamic equilibrium und thus have a separate electrochemical potential, i.e. Fermi level. When you apply a voltage VV between the systems the Fermi levels will be separated energetically by qVqV. When the metal gate and the semiconductor of a MOS structure are short circuited, they constitute a single system with one Fermi level. This corresponds to the Fermi levels being aligned for an applied zero voltage V=0