Structural morphology and optoelectronic response of Al-doped ZnWO₄ thin films fabricated via magnetron sputtering: Dependence on annealing temperature

Department of Physics and Energy, Chongqing University of Technology - Chongqing 400054, China

Received: 15 February 2026
Accepted: 2 April 2026

Abstract

/AZO/ heterofilms were deposited on p-type Si(100) single-crystal substrates via magnetron sputtering using high-purity W and Al-doped ZnO (AZO) targets. We systematically investigated the effects of annealing temperature on the microstructure, photoluminescence (PL), and photoelectric response of the as-obtained thin films. Results showed that after air annealing at 650–800° C, the heterofilms fully transformed into Al-doped ZnWO₄ with a monoclinic wolframite structure. Al³⁺ substituted for Zn²⁺ in the ZnWO₄ lattice, causing lattice contraction, generating oxygen vacancies and free carriers, and tuning the local electronic structure and carrier transport behavior. The sample annealed at 750 °C showed optimal surface compactness and crystallinity. PL measurements revealed that compared with pure ZnWO₄ prepared under identical annealing conditions, Al-doped films had a prolonged maximum lifetime of ∼26.98μ s with slightly reduced PL intensity. Al doping noticeably enhanced the conductivity and simulated sunlight photoresponse of ZnWO₄, with the 750° C-annealed sample reaching a maximum light-dark resistivity difference of 710 cm and exhibiting favorable photosensitivity. This work confirms that Al doping effectively tunes the defect structure and carrier transport of ZnWO₄, while proper annealing temperature is critical for optimizing the optoelectronic performance of Al-doped ZnWO₄ films.