Double-Heterojunction-Based HgTe Colloidal Quantum Dot Imagers

Photodetectors based on HgTe colloidal quantum dots (CQDs) are expected to enable the next generation of infrared detection technology due to their low-cost preparation, widely tunable absorption, and direct integration with Si-based electronics. However, the fabrication of HgTe CQD photodiode focal plane arrays (FPAs) has been hampered by the creation of rectifying homojunctions through delicate doping modulation and the time-consuming layer-by-layer assembly of the QD photoactive layer. Herein we address these challenges by exploring energetically favored ZnO/HgTe/ZnTe double heterojunctions (DH), and by forming colloidally stable HgTe ink that enables one-step direct film deposition. The DH HgTe CQD photodiode operates over a broad spectral range from 400 to 1800 nm, comparable to that of uncooled InGaAs detectors, with a record peak EQE of 56% at 1600 nm. A short-wave infrared (SWIR) imager has been finally demonstrated through monolithic integration with a CMOS readout integrated circuit (ROIC) comprising 640 × 512 pixels. The DH architecture is beneficial for the construction of high-performance HgTe CQD photodiodes compatible with silicon chip integration.