A low dark current and high quantum efficiency monolithic germanium-on-silicon CMOS imager technology for day and night imaging applications

A low noise, high quantum efficiency (QE) Ge photo diode was integrated in a standard 0.18 µm CMOS foundry process, enabling night imaging under moonless conditions in a high resolution CMOS image sensor (10 µm pitch, VGA). The Ge diode dark current measured at wafer probe (−45°C) in the imager chip is 25 fA per pixel and the pixel QE at λ=1.3 µm is 44% and 32% for best die at half and full VGA resolution respectively. To our knowledge this is the first large-scale integration of single crystal Ge diodes into a silicon product.