Interface-controlled broadband photodetection in Si3N4/n-Si hybrid devices

Abstract

In this study, Si3N4/n-Si hybrid photodiodes with distinct interfacial layer configurations (Si3N4-1, Si3N4-2, and Si3N4-3) were constructed and comprehensively examined to evaluate the influence of interface engineering on their optical performance. Measurements of current–voltage (I–V) under dark and illuminated settings show that the ideality factor (n) declines with increasing illumination intensity. However, the barrier height (ΦB) shows structure-dependent variation, indicating enhanced carrier transport and interface modulation. To assess device performance under varying light intensities, responsivity (R), photosensitivity (K), noise specific detectivity (D*) and equivalent power (NEP) were determined. The Si3N4-3/n-Si structure had the highest photosensitivity, while the Si3N4- 2/n-Si device showed superior overall performance with enhanced responsivity, higher detectivity, and lower NEP, indicating an optimal balance between photocarrier generation and transport. Spectral investigation confirmed a broadband response with higher external quantum efficiency (EQE) in the UV–Vis-NIR region. The linear relationship between log(Iph) and log(P) features indicates a dominating photoconduction mechanism impacted by trap states within the mobility gap. The results show that precisely controlling the Si3N4 interfacial layer improves photodiode performance by minimizing recombination losses and improving carrier dynamics. These findings show that Si3N4-based interface engineering is a promising method for producing high-performance, broadband silicon photodetectors for advanced optoelectronic applications.