1,057 research outputs found
Effects of extrinsic point defects in phosphorene: B, C, N, O and F Adatoms
Phosphorene is emerging as a promising 2D semiconducting material with a
direct band gap and high carrier mobility. In this paper, we examine the role
of the extrinsic point defects including surface adatoms in modifying the
electronic properties of phosphorene using density functional theory. The
surface adatoms considered are B, C, N, O and F with a [He] core electronic
configuration. Our calculations show that B and C, with electronegativity close
to P, prefer to break the sp3 bonds of phosphorene, and reside at the
interstitial sites in the 2D lattice by forming sp2 bonds with the native
atoms. On the other hand, N, O and F, which are more electronegative than P,
prefer the surface sites by attracting the lone pairs of phosphorene. B, N and
F adsorption will also introduce local magnetic moment to the lattice.
Moreover, B, C, N and F adatoms will modify the band gap of phosphorene
yielding metallic transverse tunneling characters. Oxygen does not modify the
band gap of phosphorene, and a diode like tunneling behavior is observed. Our
results therefore offer a possible route to tailor the electronic and magnetic
properties of phosphorene by the adatom functionalization, and provide the
physical insights of the environmental sensitivity of phosphorene, which will
be helpful to experimentalists in evaluating the performance and aging effects
of phosphorene-based electronic devices
Atomically thin group-V elemental films: theoretical investigations of antimonene allotropes
Group-V elemental monolayers including phosphorene are emerging as promising
2D materials with semiconducting electronic properties. Here, we present the
results of first principles calculations on stability, mechanical and
electronic properties of 2D antimony (Sb), antimonene. Our calculations show
that free-standing {\alpha} and \b{eta} allotropes of antimonene are stable and
semiconducting. The {\alpha}-Sb has a puckered structure with two atomic
sub-layers and \b{eta}-Sb has a buckled hexagonal lattice. The calculated Raman
spectra and STM images have distinct features thus facilitating
characterization of both allotropes. The \b{eta}-Sb has nearly isotropic
mechanical properties while {\alpha}-Sb shows strongly anisotropic
characteristics. An indirect-direct band gap transition is expected with
moderate tensile strains applied to the monolayers, which opens up the
possibility of their applications in optoelectronics
Degradation of Phosphorene in Air: Understanding at Atomic Level
Phosphorene is a promising two dimensional (2D) material with a direct band
gap, high carrier mobility, and anisotropic electronic properties.
Phosphorene-based electronic devices, however, are found to degrade upon
exposure to air. In this paper, we provide an atomic level understanding of
stability of phosphorene in terms of its interaction with O2 and H2O. The
results based on density functional theory together with first principles
molecular dynamics calculations show that O2 could spontaneously dissociate on
phosphorene at room temperature. H2O will not strongly interact with pristine
phosphorene, however, an exothermic reaction could occur if phosphorene is
first oxidized. The pathway of oxidation first followed by exothermic reaction
with water is the most likely route for the chemical degradation of the
phosphorene-based devices in air
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