Growth an‎d characterization of zinc oxide nanorods for application in optical detectors

11/4/2026 12:00:00 AM

In this research, zinc oxide (ZnO) nanorods, as nanostructures with outstan‎ding optical an‎d electronic properties, were investigated for the fabrication of ultraviolet an‎d visible light photodetectors. Due to its wide ban‎d gap (3.37 eV), high exciton binding energy (60 meV), chemical stability, biocompatibility, an‎d ease of synthesis, ZnO is considered a promising material for optoelectronic an‎d photodetection applications. In this thesis, ZnO nanorods were grown on FTO substrates using the chemical bath deposition (CBD) method. By varying the growth time (2, 3, an‎d 4 hours), samples with different structural characteristics were prepared, an‎d their structural properties were systematically analyzed. X-ray diffraction (XRD) results revealed that all samples possess a wurtzite crystal structure with a preferred (101) orientation. With increasing growth time, the intensity of the XRD peaks increased, the crystallite size became larger, an‎d slight changes in lattice parameters were observed, indicating improved crystallinity an‎d enhanced growth of the nanorods. Scanning electron microscopy (SEM) images showed that increasing the growth time from 2 to 4 hours transformed the initial nucleation stage into a stable an‎d preferential growth along the c-axis. Accordingly, the nanorod morphology evolved from a sparse an‎d disordered structure to a dense, uniform, an‎d vertically aligned array. The reduction in nanorod diameter accompanied by improved structural order an‎d complete substrate coverage confirms the dominance of axial growth an‎d enhancement of crystalline quality. These structural improvements lead to an increased effective optical surface area an‎d consequently improve the performance of the samples in photodetection an‎d electrical measurements. Moreover, it was demonstrated that at 1% iron doping significantly enhances the growth quality, increases the density, an‎d improves the structural ordering of ZnO nanorods. UV–Vis spectroscopic analysis indicated that increasing the growth time results in enhanced light absorption in the ultraviolet region. In addition, iron doping caused a red shift of the absorption edge toward the visible region, with the absorption intensity strongly dependent on both the iron concentration an‎d synthesis time. Overall, the results indicate that the chemical bath deposition method, combined with precise control of growth time, enables effective optimization of ZnO nanorod structures, leading to the fabrication of photodetectors with high sensitivity, fast response, an‎d stable performance in both the ultraviolet an‎d visible regions. These findings pave the way for the development of low-cost an‎d efficient photodetectors for applications in biomedical sensing, environmental monitoring, an‎d defense industries.

آشكارساز نوري , رسوب حمام شيميايي , اكسيد روي

Photodetector , Chemical bath deposition , Zinc oxide

Fatemeh saki

Dr. Fatemeh Debagh Kashani