Ge0.975sn0.025 320 X 256 Imager Chip For 1.6-1.9 Mu M Infrared Vision

We report the experimental fabrication and testing of a GeSn-based 320 x 256 image sensor focal plane array operating at -15 degrees C in the 1.6-1.9 mu m spectral range. For image readout, the 2D pixel array of Ge/GeSn/Ge p-i-n heterophotodiodes was flip-chip bonded to a customized silicon CMOS readout integrated circuit. The resulting camera chip was operated using back-side illumination. Successful imaging of a tungsten-filament light bulb was attained with observation of gray-scale "hot spot" infrared features not seen using a visible-light camera. The Ge wafer used in the present imaging array will be replaced in future tests by a germanium-on-silicon wafer offering thin-film Ge upon Si or on SiO2/Si. This is expected to increase the infrared responsivity obtained in back-side illumination, and it will allow an imager in a Si-based foundry to be manufactured. Our experiments are a significant step toward the realization of group IV near-mid-infrared imaging systems, such as those for night vision. (C) 2016 Optical Society of America