Solution-Processed ZnO/V2O5 Heterojunction Thin Films for UV Photodetectors

This study delineates the fabrication and evaluation of a high-performing ultraviolet (UV) photodetector (PD) consisting of a ZnO/V₂O₅ nanoparticle (NP) bilayer thin film deposited on a Si/SiO₂ substrate through spin coating. Various analytical techniques, such as X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy, have been employed to investigate the structural features and surface morphology of the as-prepared samples. The V₂O₅ NPs were prepared through a facile one-pot solvothermal process, while ZnO NPs were obtained through a rapid sol–gel method. V₂O₅ NPs demonstrate extended absorption with significant absorption in the range of 240–450 nm and exhibit a relatively smaller band gap. The optoelectronic features of as-deposited thin films have primarily been studied through I–V characteristics under dark and UV light conditions with the same external bias of 2 V, and the photocurrent has been found to be 9.13 × 10^–5 A/cm², which is ∼2.77 × 10³ times higher than the dark current. The obtained photocurrent-to-dark current ratio for the ZnO/V₂O₅ device is nearly ∼1.37 × 10² times higher than that of the ZnO-only device. Moreover, this bilayer UV PD exhibits a detectivity (D) of ∼3.1 × 10¹² Jones, a spectral responsivity (R) of ∼4 A/W, and an external quantum efficiency (EQE) of ∼16% under an external potential of 10 V. Furthermore, the findings are analyzed, and an explanation of the detailed photodetection mechanism is outlined in this paper.