Solution:

short channel effects occur in MOSFETS in which the channel length is comparable to the depletion layer widths of source and drain junctions.

These effects include:

1. Drain-induced barrier lowering (D|BL)

2. Velocity saturation

3. Hot carrier degradation.

4. Impact ionization

5. Surface scattering

DIBL is a substantial effect on short-channel devices operating near the threshold.

In short channel devices, as the source and drain get closure, they become electrostatically coupled so that the drain bias can affect the potential barrier to carrier flow at the source junction.

Therefore, the potential barrier is controlled by both the gate-to-source voltage v and the drain-to-source voltage vas.

If the drain voltage is increased, the potential Barrier in the channel decreases, leading to drain-induced barrier lowering (DIBL) leading electron flow from source to drain, even it the gate-source voltage is lower than the threshold voltage.

The channel current that flows under this condition $\left(V as\ltV_{T O}\right.$ ) is called the Threshold Subthreshold current.

Short-channel effects can be avoided by the following techniques:

• structural changes in the MOSFET design eg. Finfets and Nanowires.

• SoT technology.

• High k dielectric materials for oxides.

• Pry using compound IIIV materials.