A Monolithic Ge-on-Si CMOS Imager for Short Wave Infrared

Introduction Imaging in the Short Wave Infrared (SWIR) band (1-2μm) enables a broad range of applications in medical and dental imaging, industrial inspection and night vision. The night sky emits substantially more light in this band than in the visible. The spectral response of silicon detectors is limited to λ < ~1μm. SWIR imagers have traditionally been built using arrays of compound semiconductor detectors hybridized to a silicon read-out circuit but are prohibitively expensive for many applications. Germanium is chemically compatible with silicon and optically responsive from blue to 1.6μm but until now, there has been no good technique for integrating single-crystal germanium detectors on silicon. This paper describes a monolithic CMOS imager with Ge detectors fabricated within a conventional 180 nm CMOS foundry process.