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

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Li, Z 
Lin, ML 
Leng, YC 
Zhang, B 

jats:titleAbstract</jats:title>jats:pInformation 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 PdSejats:sub2</jats:sub>. 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.</jats:p>

40 Engineering, 4016 Materials Engineering, 4009 Electronics, Sensors and Digital Hardware
Journal Title
npj 2D Materials and Applications
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Springer Science and Business Media LLC
Engineering and Physical Sciences Research Council (EP/P020259/1)