An investigation on the visible photodetection properties of CuO-based thin films synthesized by the chemical bath deposition (CBD) method; the influence of deposition time and the annealing process

To investigate the photodetection properties of CuO-based thin films at a wavelength of 456 nm, we synthesized the as-grown layers on glass substrates via the chemical bath deposition (CBD) method for durations of 10, 15, and 20 min, subsequently annealed at 300 °C in an Ar atmosphere for 1 h, and ultimately configured in metal-semiconductor-metal (MSM) structures. We examined the layers using various techniques, including field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy, the Seebeck effect, and current-voltage (I-V) and current-time (I-t) measurements under both dark and illuminated conditions. Our findings indicate: (1) the as-grown samples exhibited a singular monoclinic CuO phase, while annealing introduced a secondary cubic Cu₂O phase; (2) the optical spectra reveal that all layers demonstrate high absorption in the visible spectrum; (3) analysis of the Seebeck effect confirms that all layers possess p-type conductivity; (4) dark I-V measurements show that the annealed layers exhibit an ohmic characteristic with electrical resistance ranging from 1.6 to 16 MΩ; and under light illumination, I-t measurements indicate that the annealed sample with the longest growth duration displays the highest photosensitivity (28%) and recovery percentage (88%).