Impact of interface defects on tunneling FET turn-on steepness

The effects of interface defects on the sharpness of the conductance switch can be seen both in the intrinsic band tail steepness (for shallow defects) observed at all temperatures, as well as in a subthreshold regime clearly dominated by thermal activation (for deep defects). To realize a steep turn-on, reduced dimensionality on both sides of the junction is needed [1]. However, increasing the tunneling probability of the device will increase not only the band-to-band current in the on-state but also leakage into the band tail. In order to achieve a turn-on steepness better than 60 mV/dec over at least six decades of current, a very high quality tunneling interface is needed, comparable to the best achieved interface trap densities in semiconductor systems. This suggests future investigation into the engineering of pristine material interfaces, possibly at atomic levels of control, with high yield.