First Investigation of Optical Properties and Local Structure of <br/>Gd<sup>3+</sup> Doped Nano-Crystalline GeSe<sub>2</sub>

Abstract

Pure and Gd-doped nano-crystalline GeSe 2 were prepared by the melt-quenching technique. The crystal structure, local structure and emission properties are investigated. Structure analysis using Rietveld program suggests monoclinic structure for both virgin and doped samples with nano-particle size 41nm for GeSe 2 and 48nm for Gd-doped sample. A wide optical band gap as estimated from absorbance measurements is 4.1ev and 4.8ev for pure and doped samples in accordance with the confinement effects. Raman spectra show two unresolved components at ~ 202 cm-1 with broad line width. Also, well identified low intensity (ʋ < 145 cm-1) and high intensity (ʋ > 250 cm-1) bands are detected. For Gd-doped sample, the main band is shifted to lower energies and its FWHM is reduced by ~ 50% accompanied by an intensity increase of about ~ 17 fold times. The photoluminescence analysis of the pure sample shows a main emission band at ~ 604 nm. This band is splitted into two separated bands with higher intensity. The detected emission bands at wavelength > 650 nm are assigned to transmission from 6 G J to the different 6 P J terms.