Phonon-Bottleneck-Governed Ultrafast Hot-Carrier Super-Diffusion in Transition Metal Dichalcogenides
Abstract
Two-dimensional transition metal dichalcogenides (TMDCs) are promising for low-power optoelectronics, yet their operational speed is widely considered constrained by low room-temperature mobilities and carrier transit delays. Here, by combining on-chip terahertz optoelectronic sampling with thermally evaporated Ohmic contacts, we eliminate external parasitic delays and directly capture the intrinsic interfacial photoresponse in unencapsulated TMDCs under zero bias. The devices achieve ultrafast relaxation lifetimes of 48.5 ps in MoS2/Au and 14.2 ps in MoSe2/Ag, translating to intrinsic 3-dB bandwidths of 4.4 GHz and 7.5 GHz, respectively. Spatial scanning and bias-dependent measurements show that this response is position-independent and bias-immune, ruling out conventional drift-limited transport and identifying hot-carrier super-diffusion driven by an interfacial electron temperature gradient as the operative mechanism. Furthermore, ultrafast pump-probe spectroscopy reveals that the macroscopic response time is quantitatively synchronized with the microscopic optical-to-acoustic phonon scattering lifetime governed by the intrinsic phonon bottleneck. Our findings establish phonon engineering as a viable paradigm to tailor non-equilibrium optoelectronic dynamics, offering a blueprint for zero-bias, ultrafast, self-powered devices.
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BibTeX
@misc{zhang2026phononbottleneckgoverned,
title = {{Phonon-Bottleneck-Governed Ultrafast Hot-Carrier Super-Diffusion in Transition Metal Dichalcogenides}},
author = {Yuwei Zhang and Dongyang Wan and Tao Zhou and Hao Wu and Junpeng Lu and Zhenhua Ni},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10500},
eprint = {2609.10500},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10500},
}
RIS
TY - UNPB
TI - Phonon-Bottleneck-Governed Ultrafast Hot-Carrier Super-Diffusion in Transition Metal Dichalcogenides
AU - Yuwei Zhang
AU - Dongyang Wan
AU - Tao Zhou
AU - Hao Wu
AU - Junpeng Lu
AU - Zhenhua Ni
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.10500
UR - https://arxiv.org/abs/2609.10500
AB - Two-dimensional transition metal dichalcogenides (TMDCs) are promising for low-power optoelectronics, yet their operational speed is widely considered constrained by low room-temperature mobilities and carrier transit delays. Here, by combining on-chip terahertz optoelectronic sampling with thermally evaporated Ohmic contacts, we eliminate external parasitic delays and directly capture the intrinsic interfacial photoresponse in unencapsulated TMDCs under zero bias. The devices achieve ultrafast relaxation lifetimes of 48.5 ps in MoS2/Au and 14.2 ps in MoSe2/Ag, translating to intrinsic 3-dB bandwidths of 4.4 GHz and 7.5 GHz, respectively. Spatial scanning and bias-dependent measurements show that this response is position-independent and bias-immune, ruling out conventional drift-limited transport and identifying hot-carrier super-diffusion driven by an interfacial electron temperature gradient as the operative mechanism. Furthermore, ultrafast pump-probe spectroscopy reveals that the macroscopic response time is quantitatively synchronized with the microscopic optical-to-acoustic phonon scattering lifetime governed by the intrinsic phonon bottleneck. Our findings establish phonon engineering as a viable paradigm to tailor non-equilibrium optoelectronic dynamics, offering a blueprint for zero-bias, ultrafast, self-powered devices.
ER -