Narrow spectral band monolithic lead chalcogenide on Si mid-IR photodetectors

Resonant cavity-enhanced detectors (RCEDs) with a narrow linewidth and high peak quantum efficiency have been realized for the first time in the mid-IR range. The detectors are fabricated with epitaxial narrow gap lead chalcogenide layers grown epitaxially on Si-substrates. They consist of an epitaxial bottom distributed Bragg mirror, a spacer layer, and the thin absorber layer followed by a metal top layer which forms the photovoltaic detector and in addition acts as top mirror. Devices with peak wavelengths varying from 4 to 8 μm, spectral widths below 1% and quantum efficiencies above 30% have been realised.