Graphene has emerged as a promising material for integration into silicon photonics, owing to its ultrafast and broadband photoresponse without the need for an external bias voltage. This photoresponse relies on the photo-thermoelectric effect created by hot carriers. A key factor underlying the performance of graphene photodetectors is the cooling dynamics of these hot carriers. In this work, we engineer these dynamics in a WSe2-graphene-WSe2 waveguide-integrated photodetector. In particular, by introducing proximity screening by a nearby graphite layer to this structure, we prolong the hot-carrier cooling time, leading to an enhanced photoresponse. We characterize the cooling dynamics under continuous-wave laser excitation by employing a photomixing technique, revealing an increase in the cooling time by up to a factor of four. Direct photoresponse measurements show that the internal photoresponsivity improves by approximately 50%. Together, these results demonstrate the potential of proximity screening to enhance the performance of graphene-based photodetectors on an integrated photonics platform.
@article{arxiv.2605.23646,
title = {Graphene-based Photodetector with Engineered Hot Carrier Cooling Dynamics},
author = {Yishu Huang and Anand Nivedan and Florian Ludwig and Bohai Liu and Michiel Debaets and Steven Brems and Hai I. Wang and Alessandro Principi and Dries Van Thourhout and Christian Haffner and Aron W. Cummings and Klaas-Jan Tielrooij},
journal= {arXiv preprint arXiv:2605.23646},
year = {2026}
}