Ultra-High Photosensitivity of Nb₂O₅/Ge Prepared via Direct Current Reactive Magnetron Sputtering Technique

The primary objective of this research is to fabricate and evaluate Nb₂O₅ thin films prepared via DC (direct current) reactive magnetron sputtering at target powers of 25 W, 50 W, and 75 W, deposited on quartz substrates and Ge wafers. The structural and morphological characteristics of the fabricated Nb₂O₅ thin films were analyzed using XRD (X-ray diffraction) and FE-SEM (field emission scanning electron microscopy), while their electrical and optical properties were characterized using UV-Vis spectrophotometry and I-V (current-voltage) tests. XRD results confirmed a natural polycrystalline structure with a hexagonal lattice, while FE-SEM imaging revealed uniform deposition and strong dependence of nanostructure size and configuration on deposition parameters. EDS (Energy-Dispersive Spectroscopy) analysis showed an increase in Nb content with higher sputtering power. The thin films demonstrated significant photosensitivity at a wavelength of 350 nm, achieving a maximum response of 514.89% at a sputtering power of 50 W. Although 350 nm was the primary wavelength tested, the UV-Vis absorbance spectra revealed a broader detection range in the UV spectrum, influenced by the DC sputtering power. Higher sputtering powers enhanced absorption in the UV range, attributed to improved film crystallinity and reduced defects, which sharpened the absorption edge. Further studies are required to assess the UV photosensitivity at additional wavelengths and determine the detection range comprehensively. Additionally, the dynamic potential of the sensors was evaluated through time-dependent response tests, indicating rapid rise and fall times suitable for real-time UV detection. These findings suggest that Nb₂O₅ thin films are promising candidates for visible-blind UV detectors and optoelectronic circuits, particularly in the UV-A range.