Phosphorene pnp junctions as perfect electron waveguides

TL;DR

This paper demonstrates that phosphorene pnp junctions can serve as perfect, lossless electron waveguides due to anti-super-Klein tunneling, enabling precise electron steering and potential applications in nanoelectronics and quantum tech.

Contribution

It introduces the concept of anti-super-Klein tunneling in phosphorene pnp junctions, showing they can act as lossless electron waveguides with broad steering capabilities.

Findings

Electrons are confined within the junction by anti-super-Klein tunneling.

Narrow electron beams propagate like light in optical fibers.

Waveguiding is lossless for specific orientations and low energies.

Abstract

The current flow in phosphorene pnp junctions is studied. At the interfaces of the junction, omni-directional total reflection takes place, named anti-super-Klein tunneling, as this effect is not due to an energetically forbidden region but due to pseudo-spin blocking. The anti-super-Klein tunneling confines electrons within the junction, which thus represents a perfect lossless electron waveguide. Calculating the current flow by applying the Green's function method onto a tight-binding model of phosphorene, it is observed that narrow electron beams propagate in these waveguides like light beams in optical fibers. The perfect guiding is found for all steering angles of the electron beam as the total reflection does not rely on the existence of a critical angle. For low electron energies and narrow junctions, the guided modes of the waveguide are observed. The waveguide operates without any loss only for a specific orientation of the junction. For arbitrary orientations, minor leakage currents are found, which however decay for low electron energies and grazing incidence angles. It is shown that a crossroad shaped pnp junction can be used to split and direct the current flow in phosphorene. The proposed device, a phosphorene pnp junction as a lossless electron waveguide, may not only find applications in nanoelectronics but also in quantum information technology.