Impurity properties of lead salt-based nanowires with electronic and dielectric quantum screening

Screened impurity properties in lead salt-based nanowire (NW) / dielectric host nanostructures containing a quasi-one-dimensional electron gas (Q1DEG) are investigated for the first time. Using the Q1D Debye-Hückel type potential characteristic of these systems, an analytical expression for the impurity binding energy is derived for the first time as a function of the NW radius R and the Q1D screening length renormalized by the dielectric screening effects. Numerical calculations are performed for realistic PbS / msSBA-15 (low-κ) and PbS / Al 2 O 3 (high-κ) NW structures, taking into account the nonparabolicity of the PbS energy bands. A strong enhancement of the impurity binding energy is predicted for both types of NWs with R=1.5 nm, while a moderate enhancement is found for low-κ NWs with R1=4.5 nm at low carrier densities. A significant suppression of the binding energy, accompanied by the formation of an impurity-induced Mott-transition region, is established for both NW types with R=4.5 nm already at moderate carrier densities (~ 0.5.10 6 cm -1 ), whereas for R=1.5 nm this occurs only at high densities (>10 6 cm -1 ). The photoionization cross-section is also analyzed as a function of incident photon energy for different NW radii and for various dielectric constant of the surrounding host medium.