Telecom Band Photodiodes Using Full Vertical MoS₂/PbS/MoTe₂ Heterostructures

The significance of fast sensing in the telecom band has been expected to keep growing due to the increasing demand for long-distance data transmission driven by advancements in AI technology. In commercial photodetectors, Ge and InGaAs are mainly used in telecom band (1260 nm ~ 1625 nm) detection. Its drawback is the complex and costly epitaxial process. In contrast, 2D transition metal dichalcogenides (TMDs) are synthesized via chemical vapor deposition (CVD)¹ and quantum dots (QDs) are fabricated through solution-based processes², both offering the potential for scalable and cost-effective production. Furthermore, QDs exhibit absorption in the C-band region (1530 nm ~ 1565 nm), which is beyond the coverage of 2D materials.³ Additionally, by replacing it with the short ligand, tetrabutylammonium iodide (TBAI)⁴, we significantly strengthened the interactions within the 2D-0D heterostructure and improved carrier properties. So we report first full vertical high-speed 2D-0D hybrid photodiode operating in the telecom band. To demonstrate a high speed 2D-0D photodiode, we adopt a MoS₂/PbS/MoTe₂ heterostructure, which can be directly related to fast charge transport via full vertical short channel.⁵ This novel structure effectively minimize the carrier pathway, leading to a significant reduction in resistance and consequently reducing time constant. Therefore it achieves a fast response speed (&lt;5 ms). We propose that our newly designed structure addresses the synergy of both 2D TMDs materials and quantum dots (QDs), and we anticipate that this approach will enable the development of devices capable of competing with sensors currently used in industry.<br/><br/>1) <i>Nature communications</i>, 2021, 12.1: 3559.<br/>2) <i>Electron</i>, 2024, 2.2: e30<br/>3) Adv. Sci. 2023:2307169.<br/>4) <i>physica status solidi (a)</i>, 2015, 212.12: 2677-2685.<br/>5) <i>The Journal of Physical Chemistry C</i>, 2021, 125.11: 6020-6025.