Electronic transport and anti-super-Klein tunneling in few-layer black phosphorous

TL;DR

This paper theoretically investigates electronic transport in few-layer black phosphorus nanoribbons, revealing highly anisotropic conductance, layer-specific current flow, and a novel anti-super-Klein tunneling phenomenon due to electron pseudo-spin effects.

Contribution

It introduces the concept of anti-super-Klein tunneling in FLBP pn junctions and analyzes its robustness against oxidation effects, advancing understanding of anisotropic quantum transport.

Findings

Transport is highly anisotropic in FLBP nanoribbons.

Electrons pass through zigzag-oriented junctions but are reflected in armchair-oriented ones.

Anti-super-Klein tunneling persists despite oxidation of the top layer.

Abstract

The electronic transport in few-layer black phosphorus (FLBP) nanoribbons is studied theoretically. The system is modeled on the basis of band-structures, which have been measured recently by $\mu$-ARPES experiments. We show that the anisotropic bands of FLBP leads to highly anisotropic transport properties; while the current in one direction can be rather focused, it can be strongly disperse in the orthogonal direction. The low-energy current is carried mainly in the central layer due to the vertical confinement of the electrons. In FLBP pn junctions, generated by the electrostatic potential of a gate contact in a certain region of the system, the electrons pass through the interface of the junction, if it is oriented along the zigzag direction of FLBP. If the junction is rotated by 90 degree and oriented along the armchair direction, the current is reflected completely for all angles of incidence and for a wide range of electron energies. This omni-directional total reflection is named anti-super-Klein tunneling as it is due to opposite pseudo-spins of the electrons in the two region of the pn junction. The effect of oxidation of the top layer of FLBP pn junctions is investigated and it is found that, while the current flow in the top layers is strongly suppressed, the anti-super-Klein tunneling persists.