INDUSTRY TRACK: Where Are the Traps? In-Depth Characterization of QD-Based Photodetectors for SWIR Imaging

Short-wavelength infrared (SWIR), which covers wavelengths ranging from 1100 to 2500 nm, plays a crucial role in a variety of applications where visible light imaging proves insufficient: SWIR is employed in fields such as surveillance, where enhanced imaging in low-light conditions is critical. In industrial inspection and quality control, SWIR aids in detecting flaws, moisture content, and other imperfections that traditional imaging methods might miss. In facial recognition technology and automotive industry, SWIR enables better identification in challenging environments, such as through fog, smoke, or glass, helping improve safety and navigation. In machine vision, SWIR facilitates more accurate analysis of materials and processes in automated systems. Overall, SWIR imaging technologies open up opportunities for innovation and enhanced performance across a wide range of sectors [1].

Compared to other SWIR detection technologies, quantum dot (QD)-based photodetectors offer simpler, more cost-effective manufacturing processes and deliver superior resolution. An additional advantage is the ability to tune their bandgap by controlling the QD size, allowing for flexibility in optimizing performance across different applications. Among these, lead sulfide (PbS) QDs represent one of the most mature technologies. However, the inclusion of heavy metals such as lead introduces environmental and regulatory challenges, impeding their broad acceptance and adaptation in industry.

Recently, heavy metal-free QD, such as indium arsenide (InAs) and indium antimonide (InSb), have gained significant attention, emerging as a promising eco-friendly alternative and paving the way for the next generation of SWIR imaging devices [2]. However, fully realizing the potential of InAs-based photodetectors requires a deeper understanding of their material properties and their impact on the device performance. In this work, we present a comprehensive analysis conducted in our laboratories, utilizing an in-depth closed-loop feedback approach to optimize materials, interfaces and devices. We also compare the emerging InAs QD devices with the more established PbS counterparts to gain deeper insights into the performance limitations of each technology, trying to answer the main question: what is hindering the device performance and how can it be solved? Our findings provide valuable insights that enable agile redesigns, resulting in substantial improvements in key performance metrics.

References

[1] Malinowski, P. E., Pejović, V., Lieberman, I., Kim, J. H., Siddik, A. B., Georgitzikis, E., ... Cheyns, D. Image sensors using thin-film absorbers. Applied Optics, 62(17), F21-F30 (2023).
[2] Leemans, J., Pejović, V., Georgitzikis, E., Minjauw, M., Siddik, A. B., Deng, Y. H., ... Hens, Z. Colloidal III–V Quantum Dot Photodiodes for Short-Wave Infrared Photodetection. Advanced Science 9.17, 2200844 (2022).