Ultrafast Hot Carrier Cooling Enabled van der Waals Photodetectors at Telecom Wavelengths.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39991776.
- Also identified by DOI 10.1021/acs.nanolett.4c05953 and PMC identifier 11887449.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Two-dimensional (2D) materials with high carrier mobility and picosecond intrinsic response times exhibit large potential for fast optoelectronics operating at telecom wavelengths. However, due to the inefficient utilization of hot carriers, 2D photodetectors for the telecom C-band have rarely been realized. Here, we report a high-performance and waveguide-free WS<sub>2</sub>/graphene photodetector operating at 1560 nm enabled by hot carrier injection and long-lived charge separation. The efficiently injected hot electrons from graphene to WS<sub>2</sub> exhibit ultrafast cooling dynamics with a 3 ps intrinsic response time. Simultaneous hole trapping in WS<sub>2</sub> ensures a long circulation of injected electrons, enabling a high responsivity of 0.26 A/W. In continuation, we present a vertical WS<sub>2</sub>/graphene/WSe<sub>2</sub> device with a built-in electric field and the same detection mechanism, for which a photocurrent on-off ratio of 3500 and an extrinsic response time of 1.71 ns are obtained. Our study highlights the benefit of combining 2D semiconductors and semimetals for high-speed photodetection.