Infrared radiation at wavelengths of 1–2 &mgr;m has been detected in a new device labeled the layered internal photoemission sensor. The device structure, which is grown by molecular beam epitaxy, incorporates epitaxial CoSi2particles with dimensions of 10–50 nm. Radiation absorbed by these particles photoexcites carriers into a surrounding single‐crystal silicon matrix. A peak quantum efficiency of 1.3% is measured, which is approximately six times higher than in planar CoSi2Schottky diodes with 5 nm silicide thickness.