11/11/2023 0 Comments Fundamental charge of electron in j![]() Studies into the effects of electron–phonon interactions on phonons include the pioneering work of Peierls 8 and later work by Kohn 9 who showed that the interactions can dramatically change the effective interatomic forces, leading to structural instability in low-dimensional systems and significant softening of phonon frequencies at specific wave vectors for three-dimensional materials, phenomena which have been verified through inelastic neutron scattering studies on metals 13. In this work, we experimentally quantify the effects of optically excited free carriers on collective phonon dynamics in silicon, revealing the direct impact of electron–phonon interactions on heat transport. While past work has shown that phonons at specific wavevectors can undergo pronounced renormalization 8, 9 or experience enhanced scattering 10, 11, 12 due to electron–phonon interactions, an open question is to what extent electron–phonon interactions can alter phonon heat conduction-the collective transport of phonons with a broad spectrum. However, electron–phonon interaction effects on phonon transport are less well characterized, both theoretically and experimentally. Given its paramount importance, electron–phonon interactions, and particularly their impact on electron transport, have been extensively studied, from Hall measurements of the collective interaction between electrons and phonons 4, 5, to the development of angle-resolved photoemission spectroscopy that resolves electronic band structure and interactions with phonons through wavevector-dependent spectral linewidths 6, 7. It is a major scattering mechanism that limits charge carrier mobility in bulk semiconductors 1, forms the basis of conventional superconductivity 2, and contributes to optical absorption in indirect-gap semiconductors 3. The electron–phonon interaction is one of the cornerstones of condensed matter physics. We also highlight the possibility of using light to dynamically control thermal transport via electron–phonon coupling. Our study provides direct experimental evidence of the elusive role of electron–phonon interaction in phonon heat transport, which is important for understanding heat conduction in doped semiconductors. The enhanced phonon scattering by photoexcited free carriers results in a substantial reduction in thermal conductivity on a nanosecond timescale. By optically exciting electron-hole pairs in a crystalline silicon membrane, we single out the effect of the phonon–carrier interaction. Here, we probe the effect of charge carriers on phonon heat transport at room temperature, using a modified transient thermal grating technique. While much progress has been made in uncovering how phonons affect electron dynamics, it remains a challenge to directly observe the impact of electrons on phonon transport, especially at environmental temperatures. As a foundational concept in many-body physics, electron–phonon interaction is essential to understanding and manipulating charge and energy flow in various electronic, photonic, and energy conversion devices.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |