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 post-annealing temperatures were tuned from room temperature to 250 °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 °C demonstrated optimal performance, reaching a responsivity of 0.27 A/W, a detectivity of 4.76 × 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.