A Silicon-Based Infra-Red Photodetector Exploiting Erbium-Doped Silicon Nanocrystals

We have exploited the interaction between erbium ions and silicon nanoclusters to produce a photodetector for use in the spectral region around 1.5 μm. The device consists of an MOS structure in which the oxide layer has been implanted with both erbium and silicon and annealed to produce silicon nanocrystals around 3 nm in diameter. Upon illumination with a 1480 nm laser diode, the well-known interaction between the nanocrystals and the rare-earth ions results in a transfer of excitation from the erbium ion to nearby silicon nanocrystals. The resultant modification of the conductivity of the oxide layer enables a current to flow when a voltage is applied.