A Silicon Photonics Waveguide-Coupled Colloidal Quantum Dot Photodiode Sensitive Beyond 1.6 Um

Silicon photonics faces a persistent challenge in extending photodetectioncapabilities beyond the 1.6 um wavelength range, primarily due to the lack ofappropriate epitaxial materials. Colloidal quantum dots (QDs) present apromising solution here, offering distinct advantages such as infraredwavelength tunability, cost-effectiveness, and facile deposition. Their uniqueproperties position them as a potential candidate for enabling photodetectionin silicon photonics beyond the conventional telecom wavelength, therebyexpanding the potential applications and capabilities within this domain. Inthis study, we have successfully integrated lead sulfide (PbS) colloidalquantum dot photodiodes (QDPDs) onto silicon waveguides using standard processtechniques. The integrated photodiodes exhibit a remarkable responsivity of 1.3A/W (with an external quantum efficiency of 74.8low 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 acompact 8-channel spectrometer incorporating an array of QDPDs. Thisachievement marks a significant step toward realizing a cost-effectivephotodetector solution for silicon photonics, particularly tailored for a widerange of sensing applications around the 2 um wavelength range.