A silicon photonics waveguide-coupled colloidal quantum dot photodiode sensitive beyond 1.6 um

TL;DR

This paper demonstrates the integration of colloidal quantum dot photodiodes onto silicon waveguides, achieving sensitive detection beyond 1.6 um, with high responsivity and low dark current, enabling scalable spectrometer applications.

Contribution

It introduces a novel integration of PbS quantum dot photodiodes on silicon photonics, extending detection capabilities beyond 1.6 um with high efficiency and scalability.

Findings

Responsivity of 1.3 A/W at 2.1 um

Low dark current of 106 nA

Successful development of an 8-channel spectrometer

Abstract

Silicon photonics faces a persistent challenge in extending photodetection capabilities beyond the 1.6 um wavelength range, primarily due to the lack of appropriate epitaxial materials. Colloidal quantum dots (QDs) present a promising solution here, offering distinct advantages such as infrared wavelength tunability, cost-effectiveness, and facile deposition. Their unique properties position them as a potential candidate for enabling photodetection in silicon photonics beyond the conventional telecom wavelength, thereby expanding the potential applications and capabilities within this domain. In this study, we have successfully integrated lead sulfide (PbS) colloidal quantum dot photodiodes (QDPDs) onto silicon waveguides using standard process techniques. The integrated photodiodes exhibit a remarkable responsivity of 1.3 A/W (with an external quantum efficiency of 74.8%) at a wavelength of 2.1 um, a low dark current of only 106 nA and a bandwidth of 1.1 MHz under a -3 V bias. To demonstrate the scalability of our integration approach, we have developed a compact 8-channel spectrometer incorporating an array of QDPDs. This achievement marks a significant step toward realizing a cost-effective photodetector solution for silicon photonics, particularly tailored for a wide range of sensing applications around the 2 um wavelength range.