Transport characteristics of multi-terminal pristine and defective phosphorene systems

Abstract

Atomic vacancies and nanopores act as local scattering centers and modify the transport properties of charge carriers in phosphorene nanoribbons (PNRs). We investigate the influence of such atomic defects on the electronic transport of multi-terminal PNR. We use the non-equilibrium Green's function approach within the tight-binding framework to calculate the transmission coefficient and the conductance. Terminals induce band mixing resulting in oscillations in the conductance. In the presence of atomic vacancies and nanopores the conductance between non-axial terminals exhibit constructive scattering, which is in contrast to mono-axial two-terminal systems where the conductance exhibits destructive scattering. This can be understood from the spatial local density of states of the transport modes in the system. Our results provide fundamental insights into the electronic transport in PNR-based multi-terminal systems and into the ability of atomic defects and nanopores through tuning the transport properties.

Hall and bend resistance of a phosphorene Hall bar

“…In summary we analyzed the electrical transport properties of a phosphorene Hall bar in the presence of a magnetic field and vacancy defects. The presence of axial and non axial terminals, with different characteris- tics, allowed us to study different transport properties of phosphorene material 21,37 (in this case, the Hall and longitudinal resistances). In Sec.…”

“…In Sec. III, we studied the pristine system where a ballistic regime was identified by the bend resistance to certain regimes of Fermi energy and magnetic field, and Landau plateaus show up in the Hall resistance mainly due the semiconductor features of the armchair terminals 8,21 . This can be seen for magnetoresistance for E F = 0.363 eV which matches a zigzag transport mode (see Fig.…”

“…This is due to the presence of a scattering region in the Hall bar, that affects the conductivity making σ xx > σ yy and also R 13,13 < R 24,24 , as explained in Ref. [ 21 ] for a cross-shaped phosphorene nanoribbon. Next, we investigate the different resistances as a function of the magnetic field for a fixed Fermi energy.…”

“…The Fermi energy E F = 0.363 eV is near to a zigzag transverse mode, which is almost magnetic-field independent 8 . Due to the metallic character, zigzag terminals induce scattering between the transport modes, not allowing the formation of quantized plateaus in the Hall resistance 21 . However, as the magnetic field increases, the energy of the zigzag Landau level differs from the Fermi energy, and the plateaus on the Hall bar are recovered.…”

“…In particular, vacancies in phosphorene were reported to exhibit a highly anisotropic and delocalized charge density, with intrinsic vacancies resulting in ingap resonance states [17][18][19] . In the absence of a magnetic field, the effects of different types of vacancies in phosphorene monolayer were theoretically investigated in multiterminal systems showing that the presence of atomic defects decrease (an increase) the longitudinal (transverse) conductance 20,21 . Studies on graphene showed that vacancy disorder can cause the appearance of new states in the Landau spectrum, which depend on the type and density of vacancies, which can be observed in the bend resistance and the density of states (DOS) 22 .…”