Silver Telluride Colloidal Quantum Dot Infrared Photodetectors and Image Sensors

TL;DR

This paper introduces environmentally-friendly silver telluride quantum dots for SWIR photodetectors, demonstrating high performance and monolithic integration potential, advancing low-cost, toxic-free infrared imaging technology.

Contribution

It reports a new synthesis method for Ag2Te quantum dots and their application in high-performance, eco-friendly SWIR photodetectors and imagers compatible with CMOS integration.

Findings

Detectivity of ~10^12 Jones at room temperature

Spectral sensitivity from 350 nm to 1600 nm

Dynamic range over 118 dB

Abstract

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 and 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 can address this challenge by enabling low-cost manufacturing and simple monolithic integration on silicon in a back-end-of-line (BEOL) process. To date, colloidal quantum dot (CQD) materials to access the SWIR are mostly based on lead sulfide (PbS) and mercury telluride (HgTe) compounds, imposing major regulatory concerns and impeding their deployment in consumer electronics due to toxicity concerns. Here we report a new synthesis method for environmentally-friendly silver telluride (Ag2Te) quantum dots and their application in high-performance SWIR photodetectors. The CQD photodetector stack employs materials compliant with the Restriction of Hazardous Substance (RoHS) directives and is sensitive in the spectral range from 350 nm - 1600 nm. The room-temperature detectivity is of the order 1012 Jones, the 3dB bandwidth is in excess of 0.1 MHz and the linear dynamic range is over 118 dB. We also realize a monolithically integrated SWIR imager based on solution processed, heavy-metal-free materials, thus paving the way of this technology to consumer electronics market.