Resonant-cavity-enhanced mid-infrared photodetector on a silicon platform

In this paper, we demonstrate high optical quantum efficiency (90%) resonant-cavity-enhanced mid-infrared photodetectors fabricated monolithically on a silicon platform. High quality photoconductive polycrystalline PbTe film is thermally evaporated, oxygen-sensitized at room temperature and acts as the infrared absorber. The cavity-enhanced detector operates in the critical coupling regime and shows a peak responsivity of 100 V/W at the resonant wavelength of 3.5 microm, 13.4 times higher compared to blanket PbTe film of the same thickness. Detectivity as high as 0.72 x 10(9) cmHz(1/2)W(-1) has been measured, comparable with commercial polycrystalline mid-infrared photodetectors. As low temperature processing (< 160 degrees C) is implemented in the entire fabrication process, our detector is promising for monolithic integration with Si readout integrated circuits.