Hot-Electron-Effect | Digital-CMOS-Design
Hot Electron Effect :
When the NMOS transistor is operated in the saturation region particularly "pinch off " condition hot carries i.e. electrons are travelling with saturation velocity and cause parasitic effects at the drain side of the channel. This effects are called as hot electron effects.
These hot electron have sufficient energy to generate the electron-hole pairs by impact ionisation. Figure shows the impact ionisation effect in the MOSFET.
The generated bulk minority carries can be collected by the drain or injected into the gate oxide. The generated majority carries create a bulk current which can be used to measure the level of the impact ionisation. The carries injection into the gate oxide lead to the hot carrier degradation effect.
The hot electrons can be also operate the trap 6 at the silicon-oxide interface. Therefore the hot electron effect limit the lifetime of the transistor. Thus energy of the hot carries depends mainly on the electric field in the pinch-off region.