INFLUENCE OF SUBSTRATE TEMPERATURE ON INFRARED PROPERTIES OF LEAD TELLURIUM SELENIDE THIN FILMS

Thin-films of lead tellurium selenide were evaporated on silicon substrates from a resource of PbTe(0.92)Se(0.08) bulk crystal grown by Bridgman method. X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive analysis by X-ray (EDAX) were used to characterize the structural and surface morphological properties, as well as chemical compositions of the thin-films. The results indicate that thin-films of lead tellurium selenide have a polycrystalline structure and a preferred orientation during the deposition. It was also revealed that the grains appear as rectangles. By comparison of the optical properties of the thin-films deposited at different substrate-temperatures, it was found that substrate temperature has an important effect on the infrared optical properties of thin-films. The refractive index of the lead tellurium selenide thin-films lies between 5.2 and 5.8, and the extinction coefficient is lower than 0.1. When the wavelength is greater than 6 mu m, the extinction coefficient of the thin-films is as less as 10(-3). It can be inferred that lead tellurium selenide is a potential material to be used in the infrared coatings.