25 research outputs found
Band structures and contact points in phosphorene superlattice
We study the band structures and the associated contact points for a
phosphorene superlattice made up of two periodic areas. We use the boundary
conditions to extract an equation describing the dispersion relation after
obtaining the eigen-wavefunctions. We show that energy transforms into linear
behavior near contact points, and fermions move at different speeds along -
and - directions. It was discovered that the periodic potential caused
additional Dirac points, which we located in -space by establishing their
positions. We demonstrate that the barrier height and width can be used to
adjust the energy gap and modify the contact points. It might be that our
findings will be useful in the development of phosphorene-based electronic
devices.Comment: 13 pages, 11 figure
Electron Scattering in Gapped Graphene Quantum Dots
Due to Klein tunneling in graphene only quasi-bound states are realized in
graphene quantum dots by electrostatic gating. Particles in the quasi-bound
states are trapped inside the dot for a finite time and they keep bouncing back
and forth till they find their way out. Here we study the effect of an induced
gap on the scattering problem of Dirac electrons on a circular
electrostatically confined quantum dot. Introducing an energy gap inside the
quantum dot enables us to distinguish three scattering regimes instead of two
in the case of gapless graphene quantum dot. We will focus on these regimes and
analyze the scattering efficiency as a function of the electron energy, the dot
radius and the energy gap. Moreover, we will discuss how the system parameters
can affect the scattering resonances inside the dot.Comment: 12 pages, 7 figure