Performance analysis of a DC magnetron sputtered Cu2O/TiO2 heterojunction photodetector for short-wavelength detection

This study details the fabrication of Cu2O/TiO2 heterostructure thin films via DC magnetron sputtering. The postannealing temperatures were tuned from room temperature to 250 degrees C to enhance their UV photodetection capabilities. X-ray diffraction (XRD) analysis confirmed the coexistence of Cu2O, CuO, and anatase TiO2 phases, with improved crystallinity and grain growth occurring at higher annealing temperatures. Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) analysis showed compact films with progressively increasing surface roughness as the annealing temperature was raised. Optical studies indicated enhanced light absorption due to a reduction in defects and improved crystalline quality. Electrical characterization demonstrated rectifying diode behavior, with annealed devices exhibiting reduced series resistance and enhanced photocurrent under UV illumination. The device annealed at 100 degrees C demonstrated optimal performance, reaching a responsivity of 0.27 A/W, a detectivity of 4.76 x 1010 Jones, a linear dynamic range (LDR) of 21.03 dB, and a rise/fall time of 611/620 ms under 395 nm UV illumination. The rapid photoresponse and increased photocurrent at higher bias voltages underscore efficient charge transport at the Cu2O/ TiO2 interface. These findings establish Cu2O/TiO2 heterostructures as highly promising materials for advanced UV photodetectors.