Compositional Plane of a New Wide-Gap Solid Solution Semiconductor CaPbSeS and Epitaxial Thin Film Growth of CaSe

We have systematically investigated the compositional plane of solubility range and lattice constants in Ca1xPbxSe1ySy system, and as a first step for preparation of the ternary system, we have also investigated the growth and characterization of the CaSe thin films. Solubility range and lattice constant of a Ca1xPbxSe1ySy system was investigated using powder synthesis under thermal equilibrium condition. A CaSe thin film was grown on a cleaved BaF2(111) substrate by means of a hot-wall epitaxy. The solubility limit at 1273K varies with respect to the Se concentration y, taking a minimum limit of 0.04 at y 0:8 and a maximum of 0.24 at y 0. It is found that the system can be lattice-matched to PbS and InP. The CaSe thin films are grown epitaxially at substrate temperature range between 673 and 873K. The energy band gap of the film is estimated to be 4.62 eV at RT through measurement of transmittance and reflectance of the film, having full-width at half-maximum (FWHM) of X-ray rocking curve of 0.08 by!{2 scan at (222) Bragg reflection