Back-side illuminated GeSn photodiode array on quartz substrate fabricated by laser-induced liquid-phase crystallization for monolithically-integrated NIR imager chip

Back-side illuminated germanium-tin (GeSn) photodiode array with high responsivity of 1.3 A/W has been demonstrated for group-IV-based near-infrared (NIR) imager chip. By using laser-induced liquid-phase crystallization technique, large-area and high-integrity photodiode array based on tensile-strained single-crystalline GeSn alloy was formed on a quartz substrate. A record-high on/off ratio of 5 decades with a low dark current of 10
⁻³
A/cm
²
was obtained at 120 K for the fabricated GeSn n
⁺
/p diode. Thanks to backside illumination, the significantly enhanced NIR photoresponse was also achieved at wavelengths of 1.55 and 2 μm.