Comparative analysis of ultraviolet photodetectors based on bismuth oxide nanosheets and germanium nanowalls: influence of ZnO/Si interface engineering on performance

This study presents a comparative analysis of ultraviolet (UV) photodetectors based on bismuth oxide nanosheets (Bi₂O₃-Nsh) and germanium nanowalls (GeNWs), both integrated on ZnO/Si heterojunction substrates and fabricated via pulsed laser ablation in liquid. A ZnO buffer layer was employed to enhance interfacial stability and electrical contact with the silicon platform. Structural, morphological, and optical properties were examined using XRD, FESEM, EDX, and UV–Vis spectroscopy, while device performance under 385 nm illumination was assessed through current–voltage analysis. Results reveal that the Bi₂O₃-Nsh/ZnO/Si photodetector significantly outperforms its GeNWs-based counterpart, achieving a responsivity of 30.3 A/W, quantum efficiency of 98.6%, sensitivity of 17,200%, gain of 173, detectivity of 6.38 × 10¹⁰ Jones, and a noise equivalent power of 0.157 × 10⁻¹² W at 6 V bias. The superior performance is attributed to favorable band alignment and efficient charge carrier separation at the Bi₂O₃ interface, highlighting its potential for high-performance UV photodetectors in environmental monitoring, flame detection, and space communication.