We have highlighted an underlying physical concept behind the BTBT process that has been mostly overlooked in literature. It has been shown that ignoring the dual nature of electrons and holes during the BTBT phenomenon can not only lead to substantially erroneous results but also to misleading conclusions. During the tunneling phenomenon, particles transit through a forbidden gap with imaginary wave-vectors. If only electron (hole) tunneling and thereby only the barrier for electrons (holes) are considered, it implies that the electron (hole) faces a barrier at the valence (conduction) band edge, and hence its wave-vector becomes imaginary there, which is unphysical because the wave-vector can be imaginary only within the bandgap and not on the valence/conduction band edge. Understanding the EHD concept is also vital for accurately determining the regime of validity of the WKB method and can thereby dispel criticisms that seem to have smeared its reputation. While all the results in this paper are presented for GNRs, the EHD concept is inherent to the physics of the BTBT process and hence is applicable to any other material.
Reference: D. Sarkar, M. Krall, and K. Banerjee, "Electron-hole Duality During Band-to-Band Tunneling Process in Graphene-Nanoribbon Tunnel-Field-Effect Transistors," Applied Physics Letters, 97, No. 26, p. 263109, Dec 27, 2010.