Compositional plane and properties of solid solution semiconductor Pb 1− xCa xS 1− ySe y for mid-infrared lasers

Abstract

We have investigated Pb 1− x Ca x S 1− y Se y solid solution semiconductor. Results obtained on bulk thermal equilibrium heat-treated samples show that the lattice constants and the energy band gaps at room temperature of the Pb 1− x Ca x S 1− y Se y system change, respectively, from 5.862 to 6.120 Å and 0.286 to around 0.9 eV. Namely, the variation of the energy band gap suggests that the Pb 1− x Ca x S 1− y Se y system covers a wide wavelength range from mid-infrared to near infrared if this quaternary solid solution is used as the active layer in a laser diode. From the results obtained by high-resolution X-ray diffraction with a four-crystal monochromator, no rhombohedral distortion is formed in Pb 1− x Ca x S thin films employing BaF 2(1 1 1) substrate and that the quality of these films is limited by mosaicity rather than slight variations of the lattice constant.