Responsivity–dark current relationship of quantum dot infrared photodetectors (QDIPs)

We studied the responsivity–dark current relationship of quantum dot infrared photodetector (QDIP) devices published by several research groups. We found that the dark currents (Ids) of these devices increased in proportion to the square of responsivity (R). Taking into consideration the photoconductive gain (g), which is considered to be equivalent to the noise gain (gn), we found that this proportionality was because g (and gn) is proportional to the square root of Id. This result indicates that, in order to improve a device’s signal-noise characteristics, it is essential to improve its internal quantum efficiency.