High-responsivity broadband photodetection of an ultra-thin InS/CIGS heterojunction on steel.

${\rm{Cu}}({\rm{In}},{\rm{Ga}}){\rm{S}}{{\rm{e}}_2}$ (CIGS) is a promising light harvesting material for large-area broadband photodetection, but it has been rarely studied up to now. Here an InS/CIGS heterojunction photodiode on steel is shown to be highly broadband photo-sensitive, with a photoresponsivity over 0.8 A/W, an external quantum efficiency over 100%, and a detectivity over 8×10 Jones from 505 to 910nm under a reverse bias of 1 V.