Tunneling current characteristics by Al+N isoelectronic traps in Si-TFET; first-principles study

Recent experiments showed that the tunneling current through Si p/n junction is remarkably enhanced when isoelectronic impurity pairs such as Al+N are doped, which is promising for realizing Si tunneling field-effect transistors. To clarify the origin of such enhancement, the tunneling probability of electron carriers assisted by an Al+N isoelectronic trap (IET) in Si p/n junction was studied based on the perturbation theory using the results of first-principles calculations. We found that the enhancement is caused by two factors; (1) IET electronic state is located in the band gap of Si and works to decrease the tunneling length as a stepping stone. (2) Due to the localization feature of IET state, the electronic transition from valence bands to the IET state increases.