Oxygen‐Controlled Structural and Defect Engineering of Magnetron‐Sputtered ZnO Thin Films for Photosensing

Zinc oxide (ZnO) thin films with a wurtzite structure were deposited by direct current magnetron sputtering under controlled O 2 :Ar ratios and nominal oxygen partial pressures to investigate the influence of oxygen‐controlled defect evolution, particularly involving oxygen vacancies (V o ) and zinc interstitials (Zn i ), on structural and ultraviolet photosensing properties. ZnO‐based UV photodetectors remain limited by the complex interplay between surface charge transfer and bulk carrier recombination. Increasing oxygen availability modifies the defect landscape and promotes preferential c‐axis orientation, reduced grain size (∼130 to ∼90 nm), decreased film thickness (∼445 to ∼105 nm), and enhanced E 2 (high) Raman characteristics. Photoluminescence measurements further indicate stronger near‐band‐edge emission and reduced defect‐assisted non‐radiative recombination in the oxygen‐rich film. The film deposited at the highest investigated O 2 :Ar ratio (3:2) exhibits the best overall photoresponse, associated with improved preferential c‐axis orientation, reduced defect‐assisted recombination, and the continued contribution of surface oxygen adsorption–desorption processes. This results in an enhanced ultraviolet photoresponse with ON/OFF ratio of ∼1.33, sensitivity of ∼97.65%, responsivity of ∼6.64 A/W, detectivity of , and external quantum efficiency (EQE) of ∼2243%. These findings demonstrate that oxygen‐controlled growth effectively tunes the structural, defect‐related, and surface charge‐transfer processes governing ultraviolet photosensing in ZnO thin films.