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

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 × 10¹¹ jones.