Effect of doping level on high-temperature operation of InAs/GaAs quantum dot infrared photodetectors

This study reports the effect of doping level on the performance of InAs/GaAs quantum-dot infrared photodetectors (QDIPs). Two QDIP samples were prepared via molecular beam epitaxy: n+-i(QDs)-n+ QDIP with undoped quantum dot (QD) active region, referred to as undoped QDIP, and n+-n(QDs)-n+ QDIPs intended to contain two electrons per QDs, referred to as doped QDIP. InAs self-assembled QDs were grown on GaAs (001) wafers by three mono-layers of InAs deposition. Both QDIPs showed a photoluminescence peak at 1.182 μm as well as a similar broad photocurrent (PC) spectrum peaked at about 7.5 μm, ranging from 4 μm to 9 μm at 5 K. Undoped QDIP yielded a PC spectrum of up to 100 K, whereas doped QDIP had a PC spectrum of up to 40 K only. This finding was mainly attributed to the lower dark current properties of undoped QDIP. Undoped QDIP at 77 K showed five orders of magnitude lower than the dark current of doped QDIP at 5 K.