Structural, morphological, and optical properties of Al-doped ZnO Material synthesized via sol-gel and spin coating: Insights into crystallinity and doping effects

Abstract

Aluminium-doped zinc oxide (AZO) thin films were synthesized on glass substrates using a sol-gel spin-coating method. The influence of Al doping on structural, morphological, and optical properties was systematically studied. X-ray diffraction revealed reduced crystallinity with increasing Al concentration, from 92.75 % (for 0 % Al) to 84.84 % (for 8 % Al). While Raman spectroscopy highlighted disorder introduced by doping, by introducing peak at 581 cm⁻¹. FESEM confirmed increased particle agglomeration in surface morphology and particle size with doping. Whereas AFM showed increased surface roughness (6.23 – 48.75) nm. Mechanistic insights into the sol-gel process revealed the formation of ZnO through hydrolysis and condensation reactions of zinc acetate, with Al³⁺ ions substituting Zn²⁺ ions in the lattice. This substitution disrupted the crystal structure, introducing geometric disorder and altering surface characteristics. Among the investigated doping concentrations, the 4 % Al-doped ZnO films exhibited smaller particles with reduced aggregation, whereas higher concentrations (6 % and 8 %) led to increased surface roughness and decreased crystallinity. These findings highlight the tunability of AZO thin films for energy-related nanotechnologies and electronic devices.