Geometric configuration for maximizing photocurrent collection in bulk photovoltaic effect devices

The bulk photovoltaic effect (BPVE) and its artificial variant generate photocurrent under zero external bias in non-centrosymmetric systems, particularly in on-chip miniaturized metasurface-based photodetectors. Despite significant advancements, enhancing the efficiency of local photocurrent collection remains a challenge, often impeded by non-uniform flow fields in graphene caused by nanoantenna contacts, which lead to carrier transport losses. In this study, we conducted a comprehensive investigation into the regulation of local photocurrent collection in zero-bias optoelectronic metasurface-based photodetectors and explored the impact of nanoantenna array configurations on photocurrent efficiency. Using a multi-layer graphene-based photodetector with V-shaped nanoantennas, we found that configuring the array layout - specifically, adopting a 5 × 5 configuration - significantly enhances responsivity, achieving an impressive 21.6 mA/W at zero bias with a considerable photocurrent of 129 nA. Through photocurrent mapping and analysis based on the Schottky-Ramo theorem, we demonstrated that non-uniform flow fields induced by nanoantenna contacts hinder local carrier transport.