The Study Of Colloidal Quantum Dot-based Infrared Photodetector

Near-infrared colloid quantum dots?QD?show some significant properties,including size-tuned bandgap and narrow emission bands.At the same time,they have solution processing for large area and low cost devices.PbS,PbSe QD can be used as near infrared light-sensitive materials of the photodetector.The performance of the QD photodetector still needs to be greatly improved in order to enable QD to achieve significant commercial value in future photodetectors.In this paper,the main research work are:Firstly,the highly responsive graphene-heterojunction?graphene between body heterojunction and substrate?infrared photodetector was studied.The photo responsivity of the graphene-heterojunction device is 10¹ A/W,while responsivity of the bulk heterojunction device is about 10^-1 A/W.Mainly due to the high carrier mobility of graphene,the responsivity of graphene-heterojunction devices is increased by two orders of magnitude.Secondly,the wide spectral response infrared photodetector based on graphene-layer heterojunction was studied.The optical responsivity of the photodetector was¹33 A/W,the external quantum efficiency was about 1×10⁴%and the detectivity is up to 9.8×10¹00 Jones.At the same time,the device exhibits a wide spectral response range from visible to infrared.Thirdly,the high switching ratio quantum dots infrared vertical photodetectors are investigated.The main performance of the photodetector was a high current switch ratio:greater than 10⁵?much higher than the reported transverse PbSe quantum dot phototransistor?,low threshold voltage and low subthreshold slope.At the same time,the device also exhibits better photoelectric properties,such as the photo responsivity of 9×10² A/W and the detectivity of 3×10¹¹ Jones.Finally,the short channel vertical infrared photodetectors based on graphene and PbS QDs hybirds were studied.The channel length of the photodetector can be reduced to the order of submicrons.Due to the high carrier mobility of graphene,the photogenerated carriers in PbS QDs were rapidly transferred to the graphene matrix,and the carriers drifted to the drain electrode in the order of picoseconds.The device had the photo responsivity and the detectivity of 2×10³ A/W and 7×10¹² Jones.