Silicon-based resonant-cavity-enchanced photodiode with a buried SiO2 reflector

We report on a silicon-based resonant cavity photodiode with a buried silicon dioxide layer as the bottom reflector. The buried oxide is created by using a separation by implantation of oxygen technique. The device shows large Fabry–Perot oscillations. Resonant peaks and antiresonant troughs are observed as a function of the wavelength, with a peak responsivity of about 50 mA/W at 650 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.