Structural, morphological, optical, and electrical studies of Tb-doped ZnO micropods elaborated by chemical bath deposition on a p-Si substrate

Terbium-doped zinc oxide microstructures with a hexagonal wurtzite structure were synthesized by a chemical bath deposition (CBD) method on p-type (100) silicon. The effects of the amount of Tb incorporated and heat treatment on the physical properties were explored. X-ray photoelectron spectroscopy (XPS) confirms the simultaneous insertion of Tb³⁺ and Tb⁴⁺ into the ZnO matrix. An increase in the Tb concentration up to 4.21% with annealing temperature is shown by energy-dispersive X-ray (EDX) measurements. Scanning electron microscopy (SEM) images show the formation of micropod ZnO with a perfectly smooth hexagonal sidewall shape. This structure of doped ZnO remained stable, although distortion of the distance and tetrahedral bonds was confirmed by XRD analysis. The luminescence spectra of the doped micropods did not show the Tb ion emission lines, proving that no energy transfer from the host to the rare-earth ions occurred. However, the visible-band emission was deformed, and the International Commission on Illumination (CIE) color emission shifted to green as the concentration of Tb increased. Near white-light emission was observed for Tb-doped ZnO micropods with concentrations higher than 1.4% and annealed at 300 °C. The color emission of the Tb-doped ZnO micropods can be tuned by varying the concentrations of Tb in the ZnO host and/or the annealing temperature, which is an interesting aspect for solid-state lighting applications. The dependence of electrical parameters on dopant concentration and annealing temperature was explored by current-–voltage (I–V) measurements, which showed a small change in barrier height with increasing dopant concentration.