Optical and photoluminescence performance of electrodeposited arsenic selenide thin film doped with erbium ion

The solid state performance of Erbium ion (Er3+), a rare-earth ion, incorporated into the lattice of arsenic selenide (As2Se3) film is here presented. By varying the concentration of the dopant from 1 to 5% (wt.%), the films were deposited on a fluorine-doped SnO2 glass via the electrodeposition method. The structural, optical and morphological characteristics of the samples were obtained using the XRD and Raman spectroscopy, UV-VIS-NIR and photoluminescence spectroscopy and scanning electron microscopy respectively. Polycrystalline films having monoclinic and cubic crystal structures for the undoped and doped samples respectively were observed from the XRD analysis. 34.5 nm and 44.2 nm were estimated for the mean grain size of the undoped and doped films respectively. The Raman spectra revealed the diffusion of the Erbium ion (Er3+) into the As2Se3 lattice by Raman shift. The films revealed least absorbance and high transmittance up to 99% in the IR region with increasing doping. A high refractive index value of 2.66 was observed for all the films with a broadening towards the NIR region. The energy bandgap was estimated and lies in the range of 3.61-3.85 eV which slightly decreased with increasing doping concentration. The PL spectra showed intense excitonic (near-edge) emission bands at 348 nm with increasing doping. SEM micrographs revealed fairly homogeneous nano-ball morphology at lower doping concentration and nanoclusters at higher doping concentration. Annealing of the films above the glass-transition temperature (T-g) allowed the transition of the film to the crystalline phase which is an interesting feature in binary chalcogenide-based phase change memory (PCM) photonics devices.