Pb-doped ZnO films: microstructural transformation and its impact on physical properties

This study investigates Pb-doped ZnO thin films grown by aerosol-assisted chemical vapor deposition (AACVD). X-ray diffraction confirms a single-phase hexagonal wurtzite structure with (100) preferred orientation for all compositions. Pb incorporation (0–10 wt%) modulates the microstructure: FE-SEM shows a transition from randomly oriented grains at low Pb to well-defined nano-needles that predominate at 5 wt%, with a mixed grain/needle morphology at 3 wt%. Scherrer analysis indicates that the crystallite size decreases up to 5 wt% (13 nm) and then slightly increases at 10 wt% (16 nm). EDX quantification tracks the solution concentration, confirming controllable Pb loading. Optical spectra reveal band gap narrowing up to 5 wt% followed by slight widening; Wemple–DiDomenico and Spitzer–Fan models describe the dispersion and free-carrier contributions. As 365 nm UV photodetectors, higher Pb films exhibit faster response and recovery but reduced responsivity and gain. These results demonstrate that Pb-induced nano-needle formation provides a tunable route to tailor optical constants and device performance in ZnO.