Glossary

Work function

Beginner

How tightly a material holds on to its electrons. Different gate materials hold them differently, which changes when a transistor turns on.

Novice

The energy needed to take an electron from a material’s Fermi level out into free space (the vacuum). The difference between the gate’s and the silicon’s work functions shifts the threshold voltage.

Expert

ψg−ψs\psi_{\mathrm{g}} - \psi_{\mathrm{s}} is the main part of VfbV_{\mathrm{fb}}. Poly gates were doped n+\mathrm{n^+} or p+\mathrm{p^+} to set it; metal gates use different metals (or work-function layers) for NMOS and PMOS, and in FinFETs a few work-function options provide the multiple VTV_{\mathrm{T}} flavors.

Explained in Bands, doping and the p-n junction (Transistors).

See also: Flat-band voltage (Vfb).

All 896 terms →