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arXiv · 2007.02034

Phonon-assisted electronic states modulation of few-layer PdSe2 at terahertz frequencies

Ziqi Li·Bo Peng·Miao-Ling Lin·Yu-Chen Leng·Bin Zhang·Chi Pang·Ping-Heng Tan·Bartomeu Monserrat·Feng Chen
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Abstract

Information technology demands high-speed optoelectronic devices, but going beyond the one terahertz (THz) barrier is challenging due to the difficulties associated with generating, detecting, and processing high-frequency signals. Here, we show that femtosecond-laser-driven phonons can be utilized to coherently manipulate the excitonic properties of semiconductors at THz frequencies. The precise control of the pump and subsequent time-delayed broadband probe pulses enables the simultaneous generation and detection processes of both periodic lattice vibrations and their couplings with electronic states. Combining ultralow frequency Raman spectroscopy with first-principles calculations, we identify the unique phonon mode-selective and probe-energy dependent features of electron-phonon interactions in layered PdSe2. Two distinctive types of coherent phonon excitations could couple preferentially to different types of electronic excitations: the intralayer (4.3 THz) mode to carriers and the interlayer (0.35 THz) mode to excitons. This work provides new insights to understand the excited-state phonon interactions of 2D materials, and to achieve future applications of optoelectronic devices operating at THz frequencies.

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Ziqi Li, Bo Peng, Miao-Ling Lin, Yu-Chen Leng, Bin Zhang, Chi Pang, Ping-Heng Tan, Bartomeu Monserrat, Feng Chen. 2021-11-26. Phonon-assisted electronic states modulation of few-layer PdSe2 at terahertz frequencies. https://doi.org/10.1038/s41699-021-00268-3

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