ZnO Doping-Induced Performance Boost in Co ₂ TiO ₄ /n-Si Schottky Self-Powered Photodetectors

In this study, we employed Co₂TiO₄ and synthesized ZnO-doped Co₂TiO₄ nanocomposites, which were utilized as interlayers in silicon-based Schottky photodetectors for optoelectronic characterization. Structural analyses using XRD, SEM, and EDX confirmed successful fabrication. The photodetectors were evaluated across a broad spectral range (351-1600 nm) and under varying light intensities. The incorporation of ZnO nanoparticles significantly enhanced the performance of the Co₂TiO₄-ZnO/n-Si device compared to its undoped counterpart. Notably, the responsivity (<i>R</i>) improved from 0.35 to 17.39 mA/W at 351 nm and from 1.75 to 23.76 mA/W at 1000 nm. Correspondingly, the specific detectivity increased by nearly an order of magnitude, surpassing 10¹⁰ Jones across much of the spectrum. The noise equivalent power (NEP) decreased drastically from 2.16 × 10^-10 to 1.03 × 10^-11 W·Hz^-1/2 at 351 nm and from 4.33 × 10^-11 to 7.53 × 10^-12 W. Hz^-1/2 at 1000 nm, indicating enhanced sensitivity. The external quantum efficiency (EQE) also improved from 0.13 to 6.43% at 351 nm, with sustained enhancement in the UV-vis-NIR regions. Under 20 mW/cm² illumination, the Co₂TiO₄-ZnO/n-Si device exhibited a responsivity of 85.99 mA/W compared to 10.23 mA/W for the Co₂TiO₄/n-Si device, and a detectivity of 4.26 × 10¹⁰ Jones, significantly higher than 1.03 × 10¹⁰ Jones for the undoped counterpart. These results demonstrate that ZnO doping significantly improves light absorption, carrier transport, and signal-to-noise ratio, making the Co₂TiO₄-ZnO/n-Si photodetector a promising candidate for high-performance, broadband, self-powered photodetection applications.