Ultra-fast on-chip VUV (λ<200 nm) photodiode integration

Abstract

In the fields of biomedicine and integrated circuits, the understanding of structural functions on the nanoscale is of great significance. However, when the size is smaller than 100 nm, the visible light cannot directly detect the structure at this scale. According to Ruili judgment, vacuum ultraviolet (VUV, 10–200 nm) can provide a channel for structural representation and imaging when the scale is smaller than 100 nm. Therefore, the use of high-space-resolution VUV microscopes can realize the device structure representation on the nanoscale. One of the vital compositions in high-space-resolution VUV microscopes is the VUV photodetector with imaging capabilities. Current commercial silicon-based imaging detectors have the disadvantage of broad spectral response. Here, an on-chip VUV photodiode integration with a vertical structure of Pt/AlN/n-Si heterojunctions was constructed on high-quality AlN thin films based on n-Si substrates using the MOCVD method, exhibiting photovoltaic responsivity and high integration. The device has an ultra-high light-to-dark ratio (∼10⁷), ultra-fast photoresponse (τ_r ∼ 12.4 ns, τ_d ∼ 49.6 ns) and high response rate (52.23 mA/W). Impressively, each array has a high degree of uniformity, reproducibility, and stability. In addition, the device can accurately detect the English letters “F” and “T”. This work not only benefits the high integration of VUV imaging sensors but also provides a new research idea for next-generation VUV microscopes with high spatial resolution.