Resonant cavity longwave SiGe-Si photodetector using a buried silicide mirror

We describe a resonant cavity detector which uses epitaxial p-type SiGe-Si quantum wells for absorption which are epitaxially grown above a high reflectance tungsten silicide layer. The device operates in the 8-12 μm band in normal incidence and exhibits a ×8 enhancement in its peak photoresponse when compared to a nonresonant control device. The black body responsivity is comparable to current n-GaAs-AlGaAs detectors at 1 V making it suitable for integration in a monolithic Si-based focal plane array. Ways to optimize the device design to achieve improved performance are discussed.