Quantum confinement and phase transition in PbS nanowire: A first principles study

Mechanism behind the switching of current induced by a gate field in a semiconducting nanowire junction

“…The atomic level structural details for the finite part of the PbSNW is taken from the optimized structure of an infinite NW, grown in the observed [100] direction. The later structure having six Pb and six S atoms in each layer along the growth direction with a lattice parameter of 6Å was calculated using the periodic DFT 19 . Only a five layer NW-structure along the growth direction is considered to build the symmetric junction with the lead (Fig.…”

Charge and spin transport in nanoscale junction from first principles

“…This higher degree of quantum confinement for a smaller diameter NW is resulting in an increase in its band gap. [115]. But when the diameter decreases, the CBM shifts towards the Γ-point, resulting in an indirect band gap behavior.…”

“…As atomic level structural details of the PbS NWs are not available a priori, we used the CCP PbS structure as the guiding point and constructed the 1D nanowire in the observed (200) growth direction. we selected two layers from the bulk structure with twelve Pb atoms and twelve S atoms and placed them in a tetragonal unit cell with guess lattice parameter c along the z-axis to construct the unit cell of the NW [115]. To avoid spurious interaction between the NW and its periodic images in the x and y-directions, we have taken a relatively large lattice parameter with a 0.72 nm of vacuum space along those two directions.…”

“…The average distance between two Pb atoms or two S atoms located at two corners of the optimized unit cell (shown in Fig. 5.1 by the dotted line) is calculated, and the covalent radii of Pb and S are added appropriately to the average distance to estimate the diameter of the NW [115]. We have used the plane wave basis functions and periodic density functional approach using the generalized gradient approximation (GGA) functional of PW91 for the exchange-correlation.…”

“…The atomic level structural details for the finite part of the PbSNW is taken from the optimized structure of an infinite NW, grown in the observed (100) direction. The later structure having six Pb and six S atoms in each layer along the growth direction with a lattice parameter of 6 Å was calculated using the periodic DFT [115]. Only a five layer NW-structure along the growth direction is considered to build the symmetric junction with the lead (Fig.…”