Drain-induced barrier lowering (DIBL): definition

Beginner

In very tiny transistors, the voltage at the far end helps open the switch a little, so it leaks more when off.

Novice

In a short channel the drain is close enough to the source that its voltage lowers the energy barrier the gate is supposed to control. The threshold voltage falls as $V_{\mathrm{DS}}$ rises, raising both on-current and leakage.

Expert

Modeled as $V_{\mathrm{t}} = V_{\mathrm{t0}} - \eta V_{\mathrm{DS}}$ , with $\eta$ (DIBL) quoted in mV/V. On a log $I_{\mathrm{D}}$ – $V_{\mathrm{GS}}$ plot it shows as a sideways shift between low- $V_{\mathrm{DS}}$ and high- $V_{\mathrm{DS}}$ curves, and it multiplies off-current by $10^{\eta \Delta V_{\mathrm{DS}}/S}$ .