Increasing Si photodetector photosensitivity in near-infrared region and manifestation of optical amplification by dressed photons

We fabricated a novel photodetector by subjecting a Si crystal having a p–n homojunction to phonon-assisted annealing. The photosensitivity of this device for incident light having a wavelength of 1.16 μm or greater was about three times higher than that of a reference Si-PIN photodiode. The photosensitivity was increased for incident light with a wavelength of 1.32 μm by applying a forward current. When the forward current density was 9 A/cm2, a photosensitivity of 0.10 A/W was achieved. This value is at least 4000 times higher than the zero-bias photosensitivity. This remarkable increase was due to the manifestation of optical amplification cause by the forward current injection. For a forward current density of 9 A/cm2, the small-signal gain coefficient of the optical amplification was 2.2×10−2, and the saturation power was 7.1×102 mW.