Paper on flexible SWIR detector

Zhang et al from the National University of Singapore published a paper titled "Flexible InGaAs/InAlAs avalanche photodiodes for short-wave infrared detection" in Nature Communications. 

Open access link: https://www.nature.com/articles/s41467-025-64401-2

Abstract: 

Flexible detectors have gained growing research interest due to their promising applications in optical sensing and imaging systems with a broad field-of-view. However, most research have focused on conventional photodiodes of which the responsivity are limited at short-wave infrared due to the absence of internal multiplication gain. Here we have realized and demonstrated flexible thin-film InGaAs/InAlAs avalanche photodiodes on a mica substrate for short-wave infrared detection. This achievement was made possible by the development and implementation of a low-temperature bonding and well-optimized fabrication process. Our devices exhibit promising characteristics, including low dark current, good responsivity, and high multiplication gain. Even when subjected to bending conditions, the avalanche photodiodes maintain their general performance. The advent of such flexible InGaAs avalanche photodiodes with reliable and promising performance enables a significantly broader range of potential applications.

a The schematics of the proposed flexible InGaAs APD chip. b The schematic of the InGaAs/InAlAs APD featuring a separate-absorption-grading-charge-multiplication structure with a metal layer served as bottom metal contact and a reflector. c Optical image of the fabricated flexible APDs under test.

a Comparison of the Jdark–V curves under flat and bent conditions where the bending radius range from 5 to 1 cm. b Comparison of the Jtotal–V characteristics with the incident power of −39.6 dBm at the same bending radius. c Comparison of the dark current at 95% of Vbr at the same bending conditions. d Comparison of the breakdown voltage at the same bending conditions. e Comparison of the responsivity at unity gain at 1550 nm at the same bending conditions. f The multiplication gain at 95% of Vbr. The J–V curves show no significant changes at all flat and bent conditions.