Question

Consider a two-terminal mos (metal-oxide-semiconductor) structure on a p-type si substrate (‘´ = 1017 /cm3 ). Assume no charges in oxide layer or at interface.

Answer 1

If there is no charge present in the oxide or at the oxide-semiconductor interface, the flatband voltage simply equals the difference between the gate metal workfunction, FM, and the semiconductor workfunction, FS.
(6.3.1)
The workfunction is the voltage required to extract an electron from the Fermi energy to the vacuum level. This voltage is between three and five Volt for most metals. The actual value of the workfunction of a metal deposited onto silicon dioxide is not exactly the same as that of the metal in vacuum. Figure 6.3.1 provides experimental values for the workfunction of different metals, as obtained from a measurement on a MOS capacitor, as a function of the measured workfunction in vacuum.