Impact of interface defects on tunneling FET turn-on steepness

Tunneling field-effect transistors (TFETs) have been investigated as a low-voltage replacement for the conventional field-effect transistor with a turn-on response steeper than 60 mV/dec. However, to date no device has achieved a steep turn-on at low voltage with an on-off ratio of 10⁶ or greater. Among the main issues is the finite density of states inside the semiconductor bandgap arising from a large concentration of interface defects [1]. Though these states do not directly conduct current, carriers can be trapped then thermally emitted to the conduction band in a trap-assisted tunneling process, broadening the switching response of the device. Overcoming these effects may not be feasible with current levels of material defects.