声子瓶颈控制的过渡金属二硫化物中超快热载流子超扩散
Phonon-Bottleneck-Governed Ultrafast Hot-Carrier Super-Diffusion in Transition Metal Dichalcogenides
- Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University（东南大学物理学院教育部量子材料与器件重点实验室）
- School of Electronic Science and Engineering, Southeast University（东南大学电子科学与工程学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过太赫兹光电子采样消除寄生延迟，发现TMDCs中热载流子超扩散受声子瓶颈控制，实现零偏压超快响应，为声子工程调控光电子动力学提供新范式。
AI中文摘要：
二维过渡金属二硫化物（TMDCs）有望用于低功耗光电子学，但其工作速度被广泛认为受限于较低的室温迁移率和载流子渡越延迟。这里，通过将片上太赫兹光电子采样与热蒸发欧姆接触相结合，我们消除了外部寄生延迟，并直接捕获了零偏压下无封装TMDCs中的本征界面光响应。器件在MoS2/Au中实现了48.5 ps的超快弛豫寿命，在MoSe2/Ag中实现了14.2 ps，分别对应4.4 GHz和7.5 GHz的本征3-dB带宽。空间扫描和偏压依赖测量表明，该响应与位置无关且不受偏压影响，排除了传统的漂移限制输运，并确定了由界面电子温度梯度驱动的热载流子超扩散作为工作机制。此外，超快泵浦-探测光谱揭示，宏观响应时间与由本征声子瓶颈控制的光学-声学声子散射寿命定量同步。我们的发现确立了声子工程作为调控非平衡光电子动力学的可行范式，为零偏压、超快、自供电器件提供了蓝图。
英文摘要：
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.
