Improved photo sensing properties of CuO thin films by doping Fe using nebulizer spray pyrolysis method

To address the escalating demand of advanced optoelectronic devices, particularly UV photodetectors, we have successfully fabricated (0, 1, 2, 3, 4, & 5 wt%) Fe-doped CuO thin films using a Nebulizer-assisted Spray Pyrolysis (NSP) technique. The films were coated on glass substrates at a temperature of 450 °C. Fundamental characterization techniques including XRD, FESEM, PL, and UV–VIS–NIR spectroscopy were conducted with a focus on the impact of Fe concentration on the structural, morphological and optical properties of the films. X-ray diffraction patterns conclude the monoclinic crystal structure with dominant peaks along the (0 0 2) and (−1 1 1) plane for all fabricated thin films and there is a increase in the crystallite size (19–28 nm) with increasing Fe dopant concentration with maximum crystallite size of 28 nm is observed for 4 wt% Fe doped CuO thin film. The analyzed FESEM images shows smooth, agglomerated, bigger trapezium-shaped, flaky irregular structures with a random porous nature. UV optical studies reveal a decrement in transmittance and a reduction in energy bandgap from 1.94 eV to 1.82 eV which demonstrates the effective alternate potential of Fe. All the fabricated thin films show band emission peaks at 410, 450, 475, and 525 nm, with the intensity variations based on Fe concentration. The photo sensing parameters of the coated thin films demonstrate optimal performance for the 4 wt% Fe-doped CuO film, with a responsivity (R) of 12.2 × 10⁻² AW⁻¹, a specific detectivity (D*) of 19.1 × 10⁸ Jones, and an external quantum efficiency (EQE) of 39.4 %, under 365 nm illumination at a bias voltage of 5 V. The identical sample evinced a fast-rising/falling time of 5.23 s/5.27 s, respectively, and evidently can be suited for UV photodetector applications.