Achieving metallurgical bonding in ZnO/CuO p-n junction via nanosecond laser irradiation

Abstract

Robust p-n heterojunctions between wide and narrow bandgap semiconductors are essential for enhancing carrier transport and improving device efficiency. However, achieving uniform metallurgical bonding and an integrated interface remains challenging due to lattice mismatches. This study demonstrates that optimized nanosecond laser irradiation successfully forms a void-free interface in CuO nanowires and ZnO film. Nano-diffraction patterns confirm the coexistence of ZnO and CuO phases at the interface, indicating robust metallurgical bonding and significant interdiffusion. Additionally, laser-induced oxygen vacancies enhance carrier density and electron migration, improving charge transport and reducing recombination rates. These improvements yield an ideality factor of ∼1.2 for the p-n junction. The optimized ZnO/CuO photodetector demonstrates a maximum photocurrent of 1.6 μA, a responsivity of 0.1 mA/W, and a detectivity of 3.95 × 10⁶ Jones, representing an 8-fold improvement compared to the unprocessed sample. This study highlights the transformative potential of laser nanojoining in advancing high-performance optoelectronic devices.