Synthesis and Characterization of Zinc Tin-Oxide (Zn–Sn–O) Thin Films for Solar Cell Application

Abdullahi Mohammed; Timtere Pascal; Dahiru Yusuf

doi:10.62292/njp.v35(S).2026.783

Authors

Mohammed Abdullahi
mohamabdulmed@gmail.com
Pascal Timtere
Yusuf Dahiru

Keywords:

Zinc tin oxide, Sn-doped ZnO, Thin films, X-ray diffraction, Electrical conductivity, Optical band gap

Abstract

This study investigates the influence of tin (Sn) doping on the structural, microstructural, electrical, and optical properties of Zn₁₋ₓSnₓO nanoparticles at four dopant concentrations: x = 0.000, 0.001, 0.003, and 0.005, designated as Samples A, B, C, and D, respectively. X-ray diffraction (XRD) analysis confirmed that all samples retained the hexagonal wurtzite ZnO structure (JCPDS 36-1451) with no detectable secondary SnO₂ phases, indicating successful substitutional incorporation of Sn into the ZnO lattice. The crystallite size varied non-monotonically, increasing from 18.34 nm (undoped) to a maximum of 20.47 nm at x = 0.003, while microstrain and dislocation density reached their minimum values at the same composition. Scanning electron microscopy (SEM) revealed progressive modifications in particle morphology and agglomeration with increasing Sn content, and energy-dispersive X-ray spectroscopy (EDS) confirmed the presence and systematic increase of Sn in the doped samples. Electrical characterization showed predominantly ohmic current–voltage behaviour for all samples. The electrical conductivity increased from approximately 26 S cm⁻¹ for the undoped sample to a maximum of approximately 51 S cm⁻¹ at x = 0.003, before declining to approximately 42 S cm⁻¹ at x = 0.005, with resistivity following the inverse trend. This non-monotonic behaviour was attributed to the competing effects of Sn⁴⁺ donor-related carrier generation and ionized impurity scattering at higher doping levels. Optical transmittance spectra showed that all films maintained greater than 90% visible transmittance with a sharp ultraviolet absorption edge. Tauc analysis yielded optical band gaps of 3.30, 3.32, 3.35, and 3.32 eV for Samples A–D, respectively, with the maximum blue-shift of 0.05 eV at x = 0.003 attributed to the Burstein–Moss effect. The slight band-gap contraction at x = 0.005 was associated with the onset of band-gap renormalization and Urbach band-tailing.

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Synthesis and Characterization of Zinc Tin-Oxide (Zn–Sn–O) Thin Films for Solar Cell Application

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