Spektroskopische Charakterisierung von mehrschaligen Mikro- und Nanoarchitekturen für Nanophononik
Experimentelle Physik der kondensierten Materie
Zusammenfassung der Projektergebnisse
The use of nontrivial geometry and topology for effective tailoring physical properties of diversified quantum fields in novel micro- and nanostructures is one of the most appealing avenues in modern nanophysics and nanotechnologies. Nanostructuring, as suggested more than two decades ago, creates a timely opportunity to search for new advanced thermoelectric materials. Self-rolled heterostructures of hybrid materials, in particular, systems of inorganic/organic, semiconductor/metal, or crystalline/amorphous heterostructures, which possess promising potential in tailoring the thermoelectric properties on demand because of varying contributions of individual components to the electron and phonon transport. Within the present project, phonon and thermal properties of Si/SiO2 multishells are studied within the complementary Elastodynamic approach and Lattice Dynamics approach. The thermal conductivity in the Si/SiO2 multishells is lower than that in the Si nanowires with the same lateral dimensions due to the acoustic mismatch of the materials and a stronger phonon confinement. A significant number of phonon modes are scattered on Si/SiO2 interfaces, what enhances the influence of boundary scattering on the thermal conductivity. Within both approaches, the thermal conductivity decreases with increase of the number of shells. The obtained thermal conductivity compares rather well with the experimental observations in the rolled-up hybrid nanomembrane superlattices. Low values of the thermal conductivity in Si/SiO2 multishells make them prospective candidates for thermoelectric applications. For characterization of vibrational excitations in multishells, BMS is an appropriate but challenging method. The key requirements for BMS characterization are revealed: the samples should not be crushed over size of the laser spot and they should be rotated in order to avoid the reflected light to enter the Fabry-Pérot interferometer. Directional Light Emission and Transmission Light Spectroscopy are proved to be appropriate methods to characterize vibrational excitations in multishell microcavities fabricated by rolling up prestrained SiOx/SiO2 nanomembranes. The study of unique directional emission induced by 3D confined light interacting with spatially tailored shape of a multishell offered new ways for manipulating emission with a higher degree of freedom. The axial direction of the microtube cavity is demonstrated to provide additional design freedom for selective mode coupling, which is achieved by carefully adjusting the axial displacement between the multishell and the microring. A “surprise” of the present project is unveiling of very strict prerequisites for the applications of BMS for characterizations of the rolled-up nanotubes. The efforts, which were undertaken towards application of the BMS method at the Center POEM (UCR) to characterize the rolledup Si/SiO2 multishells prepared at IIN, IFW Dresden, allowed us to formulate a conclusion, that samples of higher quality were needed than available. Within the assumed risk assessment and mitigation policy, we took prompt action and partly reoriented the initial plans. The multishell nanomembrane cavities fabricated by rolling up prestrained SiOx/SiO2 nanomembranes and the coupled composite cavity system compromising a rolled up microtube and a planar microring were added to the initially planned rolled-up multishells Si/SiO2 as subjects of investigation, which were measurable using the methods of 3D Directional Light Emission and Light Transmission Spectroscopy available at IIN, IFW Dresden.
Projektbezogene Publikationen (Auswahl)
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“Tailoring Electron and Phonon Energy Dispersion and Thermal transport in Nano- and Microarchitectures”, Moldavian Journal of Physical Sciences 17, 121-131 (2018)
V. M. Fomin
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“Deterministic Yet Flexible Directional Light Emission from Spiral Nanomembrane Cavities”, ACS Photonics 2019, 2537−2544 (2019)
J. Wang, Y. Yin, Y.-D. Yang, Q. Hao, M. Tang, X. Wang, C. N. Saggau, D. Karnaushenko, X. Yan, Y.-Z. Huang, L. Ma, O. G. Schmidt
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“Phonons and thermal transport in Si/SiO2 multishell nanotubes: Atomistic study”, 13 p. (12.11.2020)
C. Isacova, A. Cocemasov, D. L. Nika, V. M. Fomin
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“Selective out-of-plane optical coupling between vertical and planar microrings in a 3D configuration”, Adv. Optical Mater. 8, 2000782, 1-8 (2020)
S. Valligatla, J. Wang, A. Madani, E. S. G. Naz, Q. Hao, C. N. Saggau, Y. Yin, L. Ma, O. G. Schmidt
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“Self-rolled micro- and nanoarchitectures: Effects of topology and geometry”, De Gruyter, Berlin-Boston, 2021, 148 pp. Chapter 3. Theory of phonons in semiconductor micro- and nanoarchitectures
V. M. Fomin
