High-performance visible-SWIR dual-band Ge MSM photodetectors enhanced by in-situ segregated Al nanoparticles

We report a Ge MSM photodetector decorated with Al nanoparticles (NPs) via magnetron sputtering. Exploiting the low Al-Ge solid solubility, Al atoms spontaneously segregate and self-assemble into high-density surface NPs. The resulting localized surface plasmon resonance enhances visible-light absorption through strong scattering and local electric fields. At 405 nm, the device exhibits a ~9-fold enhancement in responsivity, reaching 0.67 A/W, with a detectivity of 1.66 × 10⁹ Jones and rapid response times (rise/fall: 0.37/0.54 μs). This work demonstrates efficient dual-band detection, providing a promising low-cost route for dual-band optoelectronic integration.