LEUVEN (Belgium), December 16, 2024— This week, at the 2024 IEEE
International Electron Devices Meeting (IEDM), imec, a world-leading
research and innovation hub in nanoelectronics and digital technologies,
and its partners in the Belgian project Q-COMIRSE, present a first of
its kind prototype shortwave infrared image sensor with indium arsenide
quantum dot photodiodes. The sensor demonstrated successful 1390 nm
imaging results, offering an environmentally friendly alternative to
first-generation quantum dots that contain lead, which limited their
widespread manufacturing. The proof-of-concept is a critical step toward
mass-market infrared imaging with low-cost and non-toxic photodiodes.
By detecting wavelengths beyond the visible spectrum, shortwave infrared
(SWIR) sensors can provide enhanced contrast and detail, as materials
reflect differently in this range. These sensors can distinguish objects
that appear identical to the human eye and penetrate through fog or
mist, making them invaluable for applications such as face recognition
or eye tracking in consumer electronics, and autonomous vehicle
navigation. While current versions are costly and limited to high-end
applications, wafer-level integration promises broader accessibility.
Quantum dots (QDs) are nanoscale semiconductor particles that can be
engineered to emit and absorb light at specific wavelengths. Tuned for
SWIR, they offer compact, low-cost absorbers, since integration into
CMOS circuits and existing manufacturing processes is possible. However,
first-generation QDs often contain toxic heavy metals such as lead and
mercury, and the search for alternatives continues.
At 2024 IEDM, imec and its partners within the Q-COMIRSE project (Ghent
University, QustomDot BV, ChemStream BV and ams OSRAM) introduced a SWIR
image sensor featuring a lead-free quantum dot alternative as absorber;
indium arsenide (InAs). The proof-of-concept sensor, tested on both
glass and silicon substrates, was the first of its kind to produce
successful 1390 nm imaging results. While QDs are considered fragile in
nature, careful selection of stack materials resulted in >300 hour
air-stability, enabling fab manufacturing compatibility. The pixel
architecture can readily be integrated with CMOS technology for image
sensing applications, but also allows flat panel display integration.
Pawel Malinowski, imec technology manager and domain lead imaging,
emphasized the significance of this breakthrough: “The first generation
of QD sensors was crucial for showcasing the possibilities of this
flexible platform. We are now working towards a second generation that
will serve as a crucial enabler for the masses – aiming at
cost-efficient manufacturing in an environmentally friendly way. With
major industry players looking into quantum dots, we are committed to
further refine this semiconductor technology towards accessible,
compact, multifunctional image sensors with new functionalities.”
Stefano Guerrieri, Engineering Fellow at ams OSRAM, added: “Replacing
lead in colloidal quantum dots with a more environmentally friendly
material was our key goal in Q-COMIRSE. Our remarkable development work
with Flemish partners imec, Ghent University, QustomDot and ChemStream
paves the way toward a low-cost and Pb-free short-wave-infrared
technology that, once mature for industrial products, could enable
unprecedented applications in robotics, automotive, AR/VR and consumer
electronics among others.”
This work was performed within the Q-COMIRSE project, funded by
SIM-Flanders (HBC.2021.0803), the spearhead cluster for materials in
Flanders, Belgium. Consortium partners included imec, Ghent University,
QustomDot BV, ChemStream BV and ams OSRAM sensor Belgium.
