title: Ge0.975Sn0.025320  ×  256 imager chip for 1.6-1.9  μm infrared vision.
abstract: We report the experimental fabrication and testing of a GeSn-based 320×256 image sensor focal plane array operating at -15°C in the 1.6-1.9 μm 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.
authors.forename: Chiao
authors.initials: C
authors.lastname: Chang
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Chien-Te
authors.initials: CT
authors.lastname: Ku
authors.forename: Shih-Guo
authors.initials: SG
authors.lastname: Yang
authors.forename: Hung Hsiang
authors.initials: HH
authors.lastname: Cheng
authors.forename: Joshua
authors.initials: J
authors.lastname: Hendrickson
authors.forename: Richard A
authors.initials: RA
authors.lastname: Soref
authors.forename: Greg
authors.initials: G
authors.lastname: Sun