Near-infrared photodetectors based on polycrystalline Ge evaporated on Si <100> substrates

We report the fabrication of efficient near-infrared photodetectors based on polycrystalline Ge films on Si (100). In view of integration with Si electronics, metal-semiconductor-metal photodiodes have been realized, for the first time to the best of our knowledge, by low-temperature evaporation. The experiments performed on non-optimized devices indicate a substantial sensitivity at both 1.32 and 1.55 μ m, with a responsivity as high as l6mA W−1 at 1.32 μm with 0.2 V bias, and a time response of about 4ns.