Heterojunction Infrared Photodiodes With High Dynamic Range Based on Lead Sulfide Quantum Dot and Zinc Oxide Nanomembrane

Abstract

Photodetectors and imagers with short-wave infrared (SWIR) sensitivities at wavelengths beyond the bandgap of silicon ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ∼ 1.1 eV) are currently subject to a rapidly expanding application space. Despite continued technological advancement, linear dynamic range and high costs associated with processing Ⅲ–Ⅴ semiconductors still limit their widespread usage. Solution-processed colloidal quantum dots (CQDs) – with tunable bandgap and strong light-matter interaction – are highly suitable as infrared absorbers for cost-effective photodetection. Here, we demonstrate a SWIR photodiode architecture with n-type zinc oxide (ZnO) nanomembrane and p-type lead sulfide (PbS) CQD thin film vertically stacked together. In the PbS CQD/ZnO nanomembrane p-n photodiode, the incident SWIR photons can be absorbed in the PbS CQD film and the photoexcited electron-hole pairs are rapidly separated by the built-in electric field. The fabricated heterojunction p-n photodiodes show a broad short-circuit photocurrent response with a peak responsivity of ∼ 75 mA/W and a maximum linear dynamic range of ∼100 dB. Finally, to demonstrate the uniformity and scalability, 16×16 photodetectors arrays (256 pixels) have been realized showing a very uniform photocurrent response with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</sub> in the range of 100 nA. As the increased maturity of large-scale film fabrication of PbS CQD along with CMOS readout integrated circuit technology, focal plane arrays can be realized based on PbS CQD/ZnO nanomembrane heterostructures.