Optical studies on Zn-doped lead chalcogenide (PbSe)100 − xZnx thin films composed of nanoparticles

• Nanoparticles of Zn doped (PbSe)100 − xZnx lead chalcogenides have been synthesized.
• Effect of laser irradiation on optical properties of (PbSe)100 − xZnx has been studied.
• A blue shift in PL spectra is obtained on Zn incorporation.

The effect of laser-Irradiation on the optical properties of Zn-doped PbSe thin films composed of nanoparticles has been studied. Scanning electron microscope (SEM) investigations suggest the formation of nanoparticles of average size of 50 nm for all the studied Zn compositions. XRD studies show that the as-prepared thin films are polycrystalline in nature. The formation of nanoparticles of Zn-doped PbSe has been confirmed by indexing the crystal planes as observed in the XRD spectra. The addition of Zn in (PbSe)100 − xZnx thin films result in the blue shift in photoluminescence spectra, this blue shift is associated with the narrowing of the band gap. Optical absorption measurements reveal a direct band gap for the present samples, which decreases on increasing the Zn content. The same trend has also been observed for the samples irradiated with laser. Further, the calculated values of Urbach energy are found to increase with the increase in Zn contents for the as-prepared as well as laser-irradiated samples. All the above observations agree well with the results of optical band gap and suggest that the decrease in band gap may be due to increase in band tails, defects and particle size.