Investigating the enhanced UV photoresponse of Cu-doped ZnO thin films synthesized via laser assisted chemical bath growth

This study introduces the novel fabrication of Cu_xZnO_(100-x) thin films (TFs) with copper (Cu) concentration levels (x) of 0.5, 1.0, 1.5, and 2.0 at% on glass substrates using the laser-assisted chemical bath growth (LACBG) method, targeting the exploration of their photoresponse for potential UV photodetector applications. Utilizing a continuous wave semiconductor laser at 444.5 nm wavelength, 5 W power, and 6 min of irradiation, high-quality Cu-doped ZnO TFs were synthesized and deposited on Ag-coated glass substrates to form MSM UV photodetectors. Structural and morphological analyses using XRD and SEM revealed vertically aligned hexagonal wurtzite nanoflowers with a c-axis orientation, while EDX confirmed Cu incorporation into the ZnO lattice. UV–visible absorbance spectra demonstrated a bandgap increase from 3.35 to 2.96 eV with higher Cu content. Enhanced UV responsiveness, particularly in the 2.0 at% Cu-doped TFs, was observed in I–V measurements under varying light conditions and bias voltages, attributed to optical confinement, a high surface-to-volume ratio, superior structural quality, and Cu-related defect-mediated carrier trapping and de-trapping. These findings indicate that Cu-doped ZnO TFs hold significant promise for UV photodetection applications.