Silicon-on-insulator resonant cavity photodiode without a slow carrier diffusion tail

We report on a novel silicon-based resonant cavity photodiode with a buried silicon dioxide layer as the bottom reflector. The buried oxide is created by using separation by implantation of oxygen technique. The device shows large Fabry-Perot oscillations. Resonant peaks and anti-resonant troughs are observed as a function of the wavelength, with a peak responsivity of about 50 mA/W at 650 nm and 709 nm. The leakage current density is 85 pA/mm² at -5 V, and the average zero-bias capacitance is 12 pF/mm². We also demonstrate that the buried oxide prevents carriers generated deep within the substrate from reaching the top contacts, thus removing any slow carrier diffusion tail from the impulse response.