Electric bias control of impurity effects in bilayer graphene

Abstract

Formation of localized impurity levels within the band gap in bigraphene under applied electric field is considered and the conditions for their collectivization at finite impurity concentration are established. It is shown that a qualitative restructuring of quasiparticle spectrum within the initial band gap and then specific metal-insulator phase transitions are possible for such disordered system at given impurity perturbation potential and concentration, such processes being effectively controlled by variation of the electric field bias. Since these effects can be expected at low enough impurity concentrations and accessible applied voltages, being stable enough thermically, they can be promising for practical applications in nanoelectronics devices.

Biased doped silicene as a way to tune electronic conduction

“…The comparative analysis of two common models for impurity perturbation on the host electronic spectrum indicates the Anderson hybrid model (adequate for transition or rare earth impurities in silicene) to be more promising for such purpose. Comparing the present system to the other known material with tunable gap, the bigraphene, where similar doping effects were recently considered [26], an advantage of the silicene host is seen in the simpler structure of its electronic spectrum. Experimental checks on the proposed regimes of doping and tunable phase transitions could better determine the field for future studies and probably open some new possibilities in this direction.…”

Collective resonances near zero energy induced by a point defect in bilayer graphene

“…Since the transport properties are essentially determined by the density of states near the Fermi level, understanding the effect of defects in low energies in BLG 26 – 42 is crucial for the fundamental studies and technology applications. Recent investigations demonstrated that defects, such as vacancies or adsorption of adatoms atom 43 – 48 , can induce pronounced peaks in the LDOS at zero energy in MLG 49 – 55 and in BLG 56 .…”

Effects of symmetry breaking in low dimensional materials

“…The Brillouin zone (BZ) was sampled with Γ-centred Monkhorst-Pack meshes [255] with 44×44×1 and 90×90×1 subdivisions for AA-and AB-BLG respectively. It was found necessary to employ the denser k-point mesh for the AA-BLG model due to differences in the DFT electronic band structure relative to the spectra expected from tight-binding theory [230,256]. The vacuum spacing between periodic images along the Z direction was set to 15…”

“…Among the numerous derivatives of the monolayer graphene (MLG) system, special interest has been given to the multi-layer allotropes [21] in particular Bernal bilayer graphene with AB stacking (AB-BLG) [230]. Like ML graphene, BL graphene also displays unconventional properties [10] that are relevant to technological developments including tunnelling field-effect transistors [231] and high-rate lithium-sulphur batteries [232,233], nanophotonics [234], sensor modelling [235], among others.…”

“…It has recently been shown that biased AB-BLG can form a Wigner crystal, due to the existence of different kinetic-energy dispersions at different electron densities [238]. The energy band gap can be tuned in proportion to the intensity of the applied bias [230], and two distinct zero-temperature quantum phases at different electron densities can be formed [238,239]. For the AB-BLG system, the presence of significant spin-orbit coupling (SOC) effects has been evidenced by topological-insulator behaviour with a finite spin Hall conductivity [240].…”