High-Performance n-CuFe2O4/p-Si Heterojunction Photodetectors: Influence of Oxygen Vacancies and Interface Engineering on Photosensitivity

In this work, we succeeded in creating an n-CuFe2O4/p-Si heterojunction photodetector characterized by its high efficiency and simple fabrication. We utilized a two-step method: first, preparing the copper ferrite powder through a sol-gel route, and then depositing it as nanostructured films using Pulsed Laser Deposition (PLD) on a 150 °C substrate. Our experiments showed that annealing the films at 400 °C for three hours was a turning point; it adjusted the oxygen vacancies enough to shift the material's conductivity to n-type, a change we confirmed using Hall effect data. Electrically, the junction performed as a strong rectifier, maintaining a Schottky barrier height of 0.74 eV. "Under visible light exposure, the sensor demonstrated a significant surge in photosensitivity, reaching peak values of 310% to 355%. This heightened response is primarily driven by the robust built-in electric field at the p-n heterojunction, which, when coupled with the substantial active surface area of the ferrite nanoparticles, facilitates the rapid dissociation and extraction of photogenerated carriers. This synergistic effect effectively mitigates charge recombination losses at the interface. The fundamental objective of this investigation was to evaluate the efficacy of defect-modulated spinel ferrites as sustainable and cost-effective active media for the next generation of wide-spectral optoelectronic devices.