On the Structural and Optical Properties of Lead Selenide Nanolayers

Abstract

It was revealed that, according to the analysis by the half-width of the X-ray lines of reflection planes (200) and (600), the sizes of subgrains in the lead selenide nanolayer ~70 nm thick made up 30-45 nm. Disorientation between the subgrains of the order of the ten thousandth of a minute and the deformation (strain) in the layer was determined by the mismatch between the layer and the substrate. It is shown that the forbidden gap width Eg of the same PbSe nanolayer determined by analyzing the optical transmission spectra by two types of straightening f (hν) and (hν)2=f (hν) coincided and made up 0.445 eV, which exceeded Eg of the unstrained PbSe layer by 0.16 eV. The total contribution of quantum effects at the given subgrain sizes and degeneracy of current carriers is less than 0.03 eV, and generally the change in the forbidden gap width was associated with deformation. Key words: dispersion, deformation, disorientation between subgrains, optical transmission, forbidden gap width.

High Deformations in Lead Selenide Nanolayers and Related New Properties

“…The increase in the lattice constant of layers is connected with the deformations formed at the substrate-layer interface, and not at the boundaries of subgrainsin this case, disorientation is minimal and makes up one hundred-thousandth of a minute. 18 Figure 3a shows the dependence of the tangential lattice constant on the growth rate of layers for the layers <100nm thick and Figure 3b shows a similar relationship for the layers 100-200 nm thick. In the dependence of the tangential lattice constant on the growth rate, for such a layer, for example, 181 nm thick, there appears the maximum of 6.150 Å at the growth rate of 6nm/s.…”

“…11 The concentration of current carriers and their mobility at 77 and 300 K were determined by four-probe method. 12,13…”