Terbium oxide doped MoO3 nanostructures: Morphology engineering and enhanced photoluminescence

Abstract

Terbium oxide doped molybdenum oxide (MoO3:Tb) nanostructures have successfully been grown by radio frequency (RF) magnetron sputtering. MoO3 nanostructures containing 1, 3, 5 and 7 wt% of terbium oxide are grown on glass substrates. X-ray diffraction (XRD) analysis shows that the MoO3:Tb nanostructures are of layered orthorhombic α-MoO3 phase. The average size of the crystallites is found to increase with increased in terbium oxide doping concentration, such that terbium oxide prompts grain growth in MoO3 matrix. The shifting of the symmetric stretching mode to lower wave numbers in the micro-Raman spectra of 5 and 7 wt% doped samples is attributed to the increase in size of the nanoparticles. FESEM and AFM images of the nanostructures with 3 wt% terbium oxide doping show the formation of nanoslabs, 5 wt% terbium oxide doping show nanorods with specific orientations and 7 wt% doping show nanotube like structures. The optical band gap energy of the nanostructures decreases from 3.46 to 3.14 eV with increase in terbium oxide doping concentration. Thicknesses of the nanostructures determined from ellipsometric analysis and vertical FESEM analysis are in the same range and they increase with increase in terbium doping concentrations. Photoluminescence spectra show that the intensity of luminescence peak increases with the increase in terbium oxide doping.