5.6.2 Depletion

5.6.2 Depletion

When the gate voltage, VG, is slightly more than zero, this causes a net negative charge at the surface of the semiconductor due to the depletion of holes from the region near the surface leaving behind uncompensated ionized acceptors [8]. The MOSFET is said to operate in the depletion mode.

Donor type interface states will be below EFS and will be filled with electrons and be neutral. Acceptor type interface states will be above EFS and be empty of electrons thus being neutral [18].

5.6.3 Inversion

When the gate voltage, VG, is further increased, the semiconductor surface is inverted from ptype to ntype. The MOSFET is said to operate in the Inversion mode [8].

Donor type interface states will be below EFS and will be filled with electrons and be neutral. Acceptor type interface states that are below EFS will be filled with electrons and become negatively charged. The acceptor type interface states that are above EFS will still be empty of electrons and remain neutral [18].