Photonics Research Group Home
Ghent University Journals/Proceedings
About People Research Publications Education Services


Publication detail

Authors: Y. Deng, C. Pang, E. Kheradmand, J. Leemans, J. Bai, M. Minjauw, J. Liu, K. Molkens, J. Beeckman, C. Detavernier, P. Geiregat, D. Van Thourhout, Z. Hens
Title: Short-Wave Infrared Colloidal QD Photodetector with Nanosecond Response Times Enabled by Ultrathin Absorber Layers
Format: International Journal
Publication date: 4/2024
Journal/Conference/Book: Advanced Materials
Volume(Issue): p.article 2402002 (8 pages)
DOI: 10.1002/adma.202402002
Citations: 3 ( - last update: 21/7/2024)
Look up on Google Scholar
Download: Download this Publication (1.7MB) (1.7MB)


Ultrafast short-wavelength infrared (SWIR) photodetection is of great interest for emerging automated vision and spatial mapping technologies. Colloidal quantum dots (QDs) stand out for SWIR photodetection compared to epitaxial (In,Ga)As or (Hg,Cd)Te semiconductors by their combining a size-tunable bandgap and a suitability for cost-effective, solution-based processing. However, achieving ultrafast, nanosecond-level response time has remained an outstanding challenge for QD-based SWIR photodiodes (QDPDs). Here, record 4 ns response time in PbS-based QDPDs that operate at SWIR wavelengths is reported, a result reaching the requirement of SWIR light detection and ranging based on colloidal QDs. These ultrafast QDPDs combine a thin active layer to reduce the carrier transport time and a small area to inhibit slow capacitive discharging. By implementing a concentration gradient ligand exchange method, high-quality p–n junctions are fabricated in these ultrathin QDPDs. Moreover, these ultrathin QDPDs attain an external quantum efficiency of 42% at 1330 nm, due to a 2.5-fold enhanced light absorption through the formation of a Fabry–Perot cavity within the QDPD and the highly efficient extraction (98%) of photogenerated charge carriers. Based on these results, it is estimated that a further increase of the charge-carrier mobility can lead to PbS QDPDs with sub-nanosecond response time.

Related Research Topics

Related Projects

Back to publication list