Controlled electron transmission by lead chalcogenide barrier potential

Abstract

Abstract Transmission of electrons across a rectangular barrier of IV–VI semiconductor compounds is considered. Conduction electrons arrive at the barrier and are reflected or transmitted through it depending on the relative values of the barrier potential V b and the electron energy E. The theory, in close analogy to the Dirac four component spinors, accounts for the boundary conditions on both sides of the barrier. The calculated transmission coefficient TC is an oscillatory function of the barrier voltage varying between zero (for full electron reflection) and unity (for full electron transmission). Character of electron wave functions outside and inside the barrier is studied. There exists a total current conservation, i.e. the sum of transmitted and reflected currents is equal to the incoming current. The transmission TC is studied for various barrier widths and incoming electron energies. Finally, the transmission coefficient TC is studied as a function of V b for decreasing energy gaps E g of different Pb1 − x Sn x Se compounds in the range of 150 meV ⩾ E g ⩾ 2 meV. It is indicated that for very small gap values the behavior of TC closely resembles that of the chiral electron tunneling by a barrier in monolayer graphene. For E g = 0 (Pb0.81Sn0.19Se) the coefficient TC reaches the value of 1 independently of V b .