8 research outputs found
Straintronics in Phosphorene: Tensile vs Shear Strains and Their Combinations for Manipulating the Band Gap
We study the effects of the uniaxial tensile strain and shear deformation as
well as their combinations on the electronic properties of single-layer black
phosphorene. The evolutions of the strain-dependent band gap are obtained using
the numerical calculations within the tight-binding (TB) model as well as the
first-principles (DFT) simulations and compared with previous findings. The
TB-model-based findings show that the band gap of the strain-free phosphorene
agrees with the experimental value and linearly depends on both stretching and
shearing: increases (decreases) as the stretching increases (decreases),
whereas gradually decreases with increasing the shear. A linear dependence is
less or more similar as compared to that obtained from the ab initio
simulations for shear strain, however disagrees with a non-monotonic behaviour
from the DFT-based calculations for tensile strain. Possible reasons for the
discrepancy are discussed. In case of a combined deformation, when both strain
types (tensile/compression + shear) are loaded simultaneously, their mutual
influence extends the realizable band gap range: from zero up to the values
respective to the wide-band-gap semiconductors. At a switched-on combined
strain, the semiconductor-semimetal phase transition in the phosphorene is
reachable at a weaker (strictly non-destructive) strain, which contributes to
progress in fundamental and breakthroughs.Comment: 16 pages,5 figures, 1 tabl
The evolution of the nanoscale dissipative structures in a distribution of defects within the isothermally irradiated f.c.c. crystal
A kinetic model for the influence of external noises such as fluctuations of the
vacanciesâ generation rate and inhomogeneity of irradiated f.c.c. crystal on the
formation of nanoscale modulated dissipative structure in a spatial distribution of
vacancies is considered. The generation rate of vacancies all over the sites and a
density of their dislocation-type sinks are modelled as independent random uniform
stationary fields and with certain defined parameters of fluctuation correlationsâ
spatial and temporal ones. Such stochastic fields can induce a spatial redistribution
of vacancies that can lead to their density stationary uniform field or
stochastic one. By the average value and correlation functions of these fluctuations,
the conditions are determined for interacting fluctuations of the vacanciesâ
density, under which this homogeneous random field becomes unstable in relation
to the stochastic field with a spatially periodic mean distribution of vacanciesâ
density. For instance, with f.c.c. nickel as a model of the irradiated functional
material, the temperature dependence of spatial period d(T) of the modulated
dissipative structure of vacanciesâ subsystem in f.c.c. crystal is numerically
forecasted and analysed, taking into account the total (âelectrochemicalâ + âstraininducedâ)
interaction between vacancies. Such d(T)-dependence is also determined
by the kinetic characteristics of vacanciesâ redistribution.The Ministry of Science and Technology, Koreahttp://www.tandfonline.com/loi/tphm202015-05-30hb201
Erratum to: Mutual influence of uniaxial tensile strain and point defect pattern on electronic states in graphene
Mutual influence of uniaxial tensile strain and point defect pattern on electronic states in graphene
The study deals with electronic properties of uniaxially stressed mono- and multi-layer graphene sheets with various kinds of imperfection: point defects modelled as resonant (neutral) adsorbed atoms or molecules, vacancies, charged impurities, and local distortions. The presence of randomly distributed defects in a strained graphene counteract the band-gap opening and even can suppress the gap occurs when they are absent. However, impurity ordering contributes to the band gap appearance and thereby re-opens the gap being suppressed by random dopants in graphene stretched along zigzag-edge direction. The band gap is found to be non-monotonic with strain in case of mutual action of defect ordering and zigzag deformation. Herewith, the minimal tensile strain required for the band-gap opening (â12.5%) is smaller than that for defect-free graphene (â23%), and band gap energy reaches the value predicted for maximal nondestructive strains in the pristine graphene. Effective manipulating the band gap in graphene requires balanced content of ordered dopants: their concentration should be sufficient for a significant sublattice asymmetry effect, but not so much that they may suppress the band gap or transform it into the âquasi- (or pseudo-) gapâ