Flexible p-i-n InAs thin-film photodetector with low dark current enabled by an InAlAs barrier

Flexible mid-infrared photodetectors are essential to realize advanced imaging applications, including wearable healthcare monitoring, security, and biomedical applications. Here, we demonstrate high-performance flexible p-i-n InAs thin-film photodetectors with an optimal In0.8Al0.2As barrier layer. This In0.8Al0.2As barrier inserted between p-InAs and UID-InAs layer reduced leakage currents by a factor of 283 by blocking the flow of electrons. The fabricated flexible device exhibited relatively low dark current densities of 1.03×10−5 at 0 V and 0.85 A/cm2 at −0.5 V, comparable to both commercially available and reported homoepitaxially-grown InAs detectors. Also, the high mechanical robustness and excellent reliability of our flexible InAs photodetector were confirmed by bending tests under various curvatures and bending cycles.