Syntheses and characterization of thin films of Te94Se6 nanoparticles for semiconducting and optical devices

Abstract

Thin films of Te94Se6 nanoparticles were synthesized using the physical vapor condensation technique at different argon (Ar) pressures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. XRD results show that the as-grown films have a polycrystalline structure. SEM images display uniform nanoparticles in these films where the size increases from ~12 to about 60nm by decreasing Ar pressure from 667 to 267Pa. These as-grown thin films were found to have direct band gaps, whose value decreases with increasing particle size. The absorption and extinction coefficients for these films were also investigated. PL emission spectra exhibit three bands peaking at 666, 718 and 760nm, while Raman spectra displayed three bands located at 123, 143 and 169cm−1. No significant changes are observed in positions or intensities of these bands by decreasing the Ar pressure, except that of the last band of PL; where the intensity increases. The obtained results on this Te94Se6 nanomaterial especially its controlled direct bandgap might be useful for development of optical disks and other semiconducting devices.