The structural properties of Pb_1-xHg_xS films of variable optical gap

Abstract

Electron diffraction and differential thermal analysis studies of solution-grown films of Pb_1-xHg_xS suggest that PbS will alloy with both phases (α and β) of HgS over a wide (up to about 33 at.% Hg) concentration range to form two different types of Pb_1-xHg_xS (semiconducting systems of variable band gap) with f.c.c. symmetry. The two alloy phases can be stabilized by choosing appropriate growth conditions. The lattice parameter and the optical band gap of the f.c.c. alloy of PbS with α-HgS increases with increasing Hg concentration in the films. The alloy of PbS with β-HgS also has an f.c.c. structure, but its lattice parameter and the optical gap decrease with increasing Hg concentration. By changing the composition up to 33 at.% Hg, the optical gap can be varied over a wide range from 0.2 to 1.2 eV.