An indium selenide cap helps black phosphorus detect visible and near-infrared light
A stacked black phosphorus/indium selenide device responded at wavelengths from 405 to 1550 nm. The upper layer also protected the black phosphorus.
Black phosphorus can absorb light over a broad spectral range, but its surface degrades on exposure to the environment. Rui Cao and colleagues covered it with indium selenide to build a vertical photoconductive detector in which the top layer was both active material and protective cap.
The device responded to illumination at visible and near-infrared wavelengths, with a measured response time of about 22 milliseconds. The cap also slowed degradation of the black phosphorus. Liyuan Zhang at SUSTech co-authored the study.