InSb/InP Core–Shell Colloidal Quantum Dots for Sensitive and Fast Short-Wave Infrared Photodetectors

Abstract

Colloidal quantum dot (CQD) technology is considered the main contender toward a low-cost high-performance optoelectronic technology platform for applications in the short-wave infrared (SWIR) to enable 3D imaging, LIDAR night vision, etc. in the consumer electronics and automotive markets. In order to unleash the full potential of this technology, there is a need for a material that is environmentally friendly, thus RoHS compliant, and possesses adequate optoelectronic properties to deliver high-performance devices. InSb CQDs hold great potential in view of their RoHS-compliant nature and�in principle�facile access to the SWIR. However, to date progress in realizing high-performance optoelectronic devices, including photodetectors (PDs), has been limited. Here, we have developed a synthesis method for producing size-tunable InSb CQDs with distinct excitonic peaks spanning a wide range from 900 to 1750 nm. To passivate the surface defects and enhance the photoluminescence (PL) efficiency of InSb CQDs, we further designed an InSb/InP core−shell structure. By employing the InSb/InP core−shell CQDs in a photodiode device stack, we report on robust InSb CQD SWIR photodetectors that exhibit an external quantum efficiency (EQE) of 25% at 1240 nm, a wide linear dynamic range exceeding 128 dB, a photoresponse time of 70 ns, and a specific detectivity of 4.4 × 10 11 jones.

Rational ligand design for enhanced carrier mobility in self-powered SWIR photodiodes based on colloidal InSb quantum dots

“…66 The BW of the sulfide-capped QPD was 63 Hz, whereas the BW of the bromide-capped QPD was 20 Hz. Compared to recent InSb QPDs, our devices exhibit a slower photoresponse speed, 61,67 but demonstrate an improved EQE at −1 V, exceeding recent reports at 1100 nm with a very low current density (Table S1, see ESI†). Despite the advancements in surface oxidation mitigation and protective shell applications over InSb CQDs, the comprehensive enhancement of all relevant figures of merit remains elusive, highlighting the complex underlying mechanisms.…”