C59-08A - Metasurface-enhanced Absorption of Colloidal Quantum Dots for IR Detection and Imaging (MetaDot IR)

The DOE seeks development of a commercially viable system for detecting shortwave infrared (SWIR) wavelengths, ranging from 1 to 2 µm. SWIR imaging is crucial in industries such as semiconductor manufacturing and agriculture, offering non-destructive and real-time detection capabilities that go beyond visible light. Current SWIR detectors, primarily based on InGaAs technology, face significant drawbacks, including high costs, large dark count noise, and the need for power-intensive cooling, making them less accessible for broader applications. Mercury cadmium telluride (MCT) is another type of photodiode material that can demonstrate similar performance in SWIR, however this technology is based on expensive epitaxy processes. These limitations hinder the widespread adoption of SWIR sensors despite their potential benefits. Colloidal quantum dot (CQD)-based photodetectors (PDs) have emerged as promising candidates in the areas of IR sensing and imaging. These detectors use mercury telluride (HgTe), lead sulfide (PbS), and lead selenium (PbSe) CQDs in liquid form. HgTe in particular allows for wide response over the entire IR spectrum due to its highly tunable energy band gap, and imaging systems that utilize HgTe CQDs can operate reasonably well at room temperature in the SWIR range. Since synthesis of CQD PDs use a liquid-based approach, arrays of these detectors can be coated directly onto silicon-based readout integrated circuits (Si-ROICS) at wafer-scales, without expensive flip-chip bonding and metal interconnects. Moreover, device designs that leverage metasurfaces in conjunction with CQDs can enhance responsivity and overall performance of the photodetection system. Quantum Ventura, experts in AI/ML, propose to develop a high performance, uncooled IR imaging system utilizing metasurfaces to enhance the absorption of CQDs during photodetection. CQD detectors can be integrated monolithically with small-pixel-pitch, high-resolution silicon readout integrated circuit (Si-ROIC) arrays, bypassing the expensive hybridization process required by InGaAs, MCT, and InSb-based detectors. Moreover, CQD “ink” can be coated, printed, or otherwise deposited into direct electrical contact with Si-ROICs, enabling high-throughput production. With metasurface structures, it is possible to realize a 10-fold increase in absorption/responsivity compared to quantum dot (QD) thin films with the same thickness but without these structures. Appropriate geometry and placement of constituent scattering elements for each metasurface can be precisely determined using distributed ML methods. As part of Phase I, we will model trade-offs of device parameters, such as quantum efficiency, dynamic range, dark current levels, and spectral response range, as well as downselect materials and geometry for metasurface design elements. We will use previously developed ML methods to uncover the connection between unit-cell geometry and EM scattering, as well as solve the inverse model permitting specification of the geometry given a desired scattering response. The overall goal of the project is to develop a more cost-effective, energy-efficient SWIR detection alternative that can compete with state-of-the-art detectors currently based on InGaAs, MCT, and InSb.