Characterization, Thermal Effect on Optical Band Gap Energy and Photoluminescence in Wurtzite ZnO:Er Nanocrystallites

Abstract

Zinc Oxide is an extensively studied group II-VI Semiconductor with optical properties that permits stable emission at room temperature, having immense applications in sensors, field emission and photonic devices. It exhibits a wide variety of morphologies in the nano regime. XRD, FTIR, EDAX and TEM spectra have been used for characterizing the material. The percentage of doping material is confirmed from the EDAX spectrum. The XRD results indicated that the particle size of nano ZnO: Er is much small as compared to that of pure ZnO and decreases with the Erbium loading. XRD has shown that as temperature increases, particle size also increases. The UV Absorption spectra showed blue shift towards 208nm due to doping with Er. From the position of the absorption spectra is shifted towards the lower wavelength side or known as blue-shifted relative to undoped ZnO. The band gap energy of Er-doped ZnO nanoparticles at 120 and 200oC are determined using Tauc plot and found to be in the range 3.321eV. It was found that energy band gap Eg increases with doping of Er. As temperature increases the band gap energy decreases. The Photo-Luminescence study was carried out on this material and observed longer wavelength shift for emission peaks on calcination. The analysis of optical properties shows that ZnO: Er is a promising material and has potential application in optoelectronic devices. Doping of Er changed the free carrier concentration in the ZnO nanoparticles.