Graphene germanium on insulator GGOI Schottky diode photodetector

Abstract We report a novel, low-cost, and CMOS-compatible hybrid graphene/Ge-on-insulator (GGOI) photodetector designed to meet the growing demands of next-generation datacom, AI interconnects, and co-packaged optics (CPO). By integrating a CVD graphene electrode onto a high-quality, 800 nm-thick GOI absorber via an ultrathin GeOₓ interfacial layer, this architecture offers a highly scalable approach to hybrid 2D/bulk photonic devices. In this design, the graphene layer plays a critical role: it acts as an extended electrode that homogenizes the electric-field distribution and mitigates the influence of interfacial defect states. This interface engineering significantly improves carrier injection and collection, transforming a non-ideal MIS contact into an enhanced-collection photodetector with marked rectification. Under monochromatic illumination at 578 nm and moderate reverse polarization ( − 2.5 V), the device achieves a responsivity of 0.446 A/W, an exceptional external quantum efficiency (EQE) of ≈ 95.6%, and a shot noise-limited specific detectivity of ≈ 2.3 × 10 10 Jones. Furthermore, the photodetector exhibits a stable and reproducible response to pulsed optical excitation even at ultra-low bias ( < 0.5 V). These results establish the AuPd/G/GOI structure as a promising, energy-efficient solution for low-power photodetection in advanced silicon photonics platforms.