Silicon meta-atom-enabled self-powered selectively patterned black silicon photodetector for real-time monitoring of sunlight

Abstract

Epitaxy-free, c-axis oriented, unidirectional ZnO nanospikes were grown by oxygen-assisted radio frequency (RF) magnetron sputtering, and the thickness of the ZnO layer was optimized to fabricate self-powered photodetector devices. The heterojunction photodetectors fabricated with a selectively grating-patterned black silicon substrate and the optimized ZnO nanospikes layer achieved a self-powered detectivity of 5.25 × 10¹¹ Jones under a broad electromagnetic spectrum. Colloidal Mie-resonant silicon nanoparticles, spin-coated on the fingers of the front metal electrode of the devices, sharply increased the detectivity to 83.6-fold higher than the uncoated devices. The multiple electric and magnetic resonant peaks that emerged from the varied dimensions of SiNP aided absorption of light across a broad spectrum of wavelengths, which was evident from finite-difference time-domain simulations and diffuse reflectance spectroscopy studies. This broadband absorption aided the photodetector device to achieve the most competitive self-powered detectivity of 1.26 × 10¹⁴ Jones under a power density of 83.3 mW cm⁻². Under ambient conditions, the devices maintained their self-powered nature, even after one year, showing a detectivity of 4.9 × 10⁹ Jones. A realistic application of the self-powered device monitoring outdoor sunlight was demonstrated with a future outlook toward applications in greenhouse farming, climate monitoring, and so on. Additionally, this study opens up a new avenue for utilizing dielectric SiNP for applications that require broadband absorption of light in photodetection, photovoltaics, and photocatalysis.