High performance NIR photodetector based on Cd(1-x)CuxS colloidal quantum dots thin films

Abstract

Thin films of Cd(1-x)CuxS (x = 0.0 to 0.05 with interval of 0.01) colloidal quantum dots (CQDs) are employed to develop NIR photodetectors (PDs) with significantly high performance parameters and selectivity. Two very cost effective and easy chemical routes are used to synthesize Cd(1-x)CuxS CQDs and to fabricate the PD devices. The Cd(1-x)CuxS CQDs thin films are primarily characterized by various techniques in order to study the influence of Cu doping on different properties of the films. Further, the impact of doping on device performance under the exposure of laser light of different wavelengths is investigated. The tunability in sensing range from visible (635 nm) to NIR (782 nm) of the PDs with a huge improvement in selectivity and device performance due to the incorporation of the dopant is noticed. The maximum selectivity is observed for device S2 (2% Cu in CdS) with maximum responsivity and external quantum efficiency of ∼39 A/W and ∼6.2 × 103% respectively. Whereas the device S4 (4% Cu in CdS) is found to be the fastest with response times of 102 ms/109 ms, sensitivity of ∼3 × 105%, and detectivity of ∼1 × 1014 cmHz1/2W−1. In present study, device S4shows best optimal performance parameters.