Structural morphology and optoelectronic response of Al-doped ZnWO

$\text{WO}{}_{3}$ /AZO/$\text{WO}{}_{3}$ 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 $\text{M}\Omega {}\cdot {}$ 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.