  Photodetectors that are sensitive in shortwave infrared (SWIR) range (1 um -
2 um) are of significant interest for applications in 3D, night and adverse
weather imaging, machine vision, autonomous driving, among others. Currently
available technologies in the SWIR rely on costly epitaxial semiconductors that
are not monolithically integrated with CMOS electronics. Solution-processed
quantum dots have been developed to address this challenge enabling low-cost
manufacturing and facile monolithic integration on silicon in a
back-end-of-line (BEOL) process. To date, colloidal quantum dot (CQD) materials
to access the SWIR have been based on lead sulfide (PbS) and mercury telluride
(HgTe) compounds imposing major regulatory concerns and impeding their
deployment in consumer electronics. Here we report a novel synthetic method of
environmentally friendly silver telluride quantum dots and their application in
high-performance SWIR photodetectors. The CQD photodetector stack is entirely
based on Restriction of Hazardous Substance (RoHS) compliant materials and
exhibits a spectral range from 350 nm - 1600 nm, with room-temperature
detectivity of the order 1012 Jones, 3dB bandwidth in excess of 0.1 MHz and
linear dynamic range of over 118 dB. We further demonstrate, for the first
time, a monolithically integrated SWIR imager that is based on
solution-processed, heavy-metal-free materials, paving the way of this
technology to consumer electronics market.

Applied Physics