Phonon properties and unconventional heat transfer in a
quasi-two-dimensional Bi2O2Se crystal

J 2025

Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal

ZICH, Jan; Antonin SOJKA; Petr LEVINSKY; Martin MISEK; Kyo-Hoon AHN et. al.

Basic information

Original name

Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal

Authors

ZICH, Jan; Antonin SOJKA; Petr LEVINSKY; Martin MISEK; Kyo-Hoon AHN; Jiri NAVRATIL; Jiri HEJTMANEK; Karel KNIZEK; Václav HOLÝ (203 Czech Republic, belonging to the institution); Dmitry NUZHNYY; Fedir BORODAVKA; Stanislav KAMBA and Cestmir DRASAR

Edition

Physical Review Materials, American Physical Society, 2025, 2475-9953

Other information

Language

English

Type of outcome

Article in a journal

Field of Study

10302 Condensed matter physics

Country of publisher

United States of America

Confidentiality degree

is not subject to a state or trade secret

References:

URL URL

Impact factor

Impact factor: 3.400 in 2024

Organization unit

Faculty of Science

DOI

https://doi.org/10.1103/PhysRevMaterials.9.054603

UT WoS

001495036600002

EID Scopus

2-s2.0-105004739038

Keywords in English

Density of states; Electrical conductivity; First-principles calculations; Hall effect; Optical & microwave phenomena; Permittivity; Phonons; Specific heat; Thermal conductivity

Abstract

In the original language

Bi2⁢O2⁢Se belongs to a group of quasi-2D semiconductors that can replace silicon in future high-speed/low-power electronics. However, the correlation between crystal/band structure and other physical properties still eludes understanding: carrier mobility increases non-intuitively with carrier concentration; the observed T2 temperature dependence of resistivity lacks explanation. Moreover, a very high relative out-of-plane permittivity of about 150 has been reported in the literature. A proper explanation for such a high permittivity is still lacking. We have performed infrared (IR) reflectivity and Raman scattering experiments on a large perfect single crystal with defined mosaicity, carrier concentration, and mobility. Five of the eight phonons allowed by factor group theory have been observed and their symmetries determined. The IR spectra show that the permittivity measured in the tetragonal plane is as high as ɛ𝑟≈500, and this high value is due to a strong polar phonon with a low frequency of ∼34 cm−1 (∼1 THz). Such an unusually high permittivity allows the screening of charge defects, leading to the observation of high electron mobility at low temperatures. It also allows effective modulation doping providing a platform for high-performance 2D electronics. DFT calculations suggest the existence of a very low-frequency acoustic phonon ∼14 cm−1 (∼0.4 THz). Both the low-frequency phonons cause anomalous phonon DOS, which is reflected in the unconventional temperature dependence of the heat capacity, 𝐶𝑝≈T3.5. The temperature-dependent, two-component group velocity is proposed to explain the unusual temperature dependence of the thermal conductivity, 𝜅≈T1.5.

Links

90237, large research infrastructures

Name: CEMNAT III

Cite

ZICH, Jan; Antonin SOJKA; Petr LEVINSKY; Martin MISEK; Kyo-Hoon AHN; Jiri NAVRATIL; Jiri HEJTMANEK; Karel KNIZEK; Václav HOLÝ; Dmitry NUZHNYY; Fedir BORODAVKA; Stanislav KAMBA and Cestmir DRASAR. Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal. Physical Review Materials. American Physical Society, 2025, vol. 9, No 5, p. 1-10. ISSN 2475-9953. Available from: https://doi.org/10.1103/PhysRevMaterials.9.054603.

@article{2501654,
   author = {Zich, Jan and Sojka, Antonin and Levinsky, Petr and Misek, Martin and Ahn, KyoandHoon and Navratil, Jiri and Hejtmanek, Jiri and Knizek, Karel and Holý, Václav and Nuzhnyy, Dmitry and Borodavka, Fedir and Kamba, Stanislav and Drasar, Cestmir},
   article_number = {5},
   doi = {https://doi.org/10.1103/PhysRevMaterials.9.054603},
   keywords = {Density of states; Electrical conductivity; First-principles calculations; Hall effect; Optical & microwave phenomena; Permittivity; Phonons; Specific heat; Thermal conductivity},
   language = {eng},
   issn = {2475-9953},
   journal = {Physical Review Materials},
   title = {Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal},
   url = {https://doi.org/10.1103/PhysRevMaterials.9.054603},
   volume = {9},
   year = {2025}
}

TY  - JOUR
ID  - 2501654
AU  - Zich, Jan - Sojka, Antonin - Levinsky, Petr - Misek, Martin - Ahn, Kyo-Hoon - Navratil, Jiri - Hejtmanek, Jiri - Knizek, Karel - Holý, Václav - Nuzhnyy, Dmitry - Borodavka, Fedir - Kamba, Stanislav - Drasar, Cestmir
PY  - 2025
TI  - Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal
JF  - Physical Review Materials
VL  - 9
IS  - 5
SP  - 1-10
EP  - 1-10
PB  - American Physical Society
SN  - 24759953
KW  - Density of states
KW  - Electrical conductivity
KW  - First-principles calculations
KW  - Hall effect
KW  - Optical & microwave phenomena
KW  - Permittivity
KW  - Phonons
KW  - Specific heat
KW  - Thermal conductivity
UR  - https://doi.org/10.1103/PhysRevMaterials.9.054603
N2  - Bi2⁢O2⁢Se belongs to a group of quasi-2D semiconductors that can replace silicon in future high-speed/low-power electronics. However, the correlation between crystal/band structure and other physical properties still eludes understanding: carrier mobility increases non-intuitively with carrier concentration; the observed T2 temperature dependence of resistivity lacks explanation. Moreover, a very high relative out-of-plane permittivity of about 150 has been reported in the literature. A proper explanation for such a high permittivity is still lacking. We have performed infrared (IR) reflectivity and Raman scattering experiments on a large perfect single crystal with defined mosaicity, carrier concentration, and mobility. Five of the eight phonons allowed by factor group theory have been observed and their symmetries determined. The IR spectra show that the permittivity measured in the tetragonal plane is as high as ɛ𝑟≈500, and this high value is due to a strong polar phonon with a low frequency of ∼34 cm−1 (∼1 THz). Such an unusually high permittivity allows the screening of charge defects, leading to the observation of high electron mobility at low temperatures. It also allows effective modulation doping providing a platform for high-performance 2D electronics. DFT calculations suggest the existence of a very low-frequency acoustic phonon ∼14 cm−1 (∼0.4 THz). Both the low-frequency phonons cause anomalous phonon DOS, which is reflected in the unconventional temperature dependence of the heat capacity, 𝐶𝑝≈T3.5. The temperature-dependent, two-component group velocity is proposed to explain the unusual temperature dependence of the thermal conductivity, 𝜅≈T1.5.
ER  -

ZICH, Jan; Antonin SOJKA; Petr LEVINSKY; Martin MISEK; Kyo-Hoon AHN; Jiri NAVRATIL; Jiri HEJTMANEK; Karel KNIZEK; Václav HOLÝ; Dmitry NUZHNYY; Fedir BORODAVKA; Stanislav KAMBA and Cestmir DRASAR. Phonon properties and unconventional heat transfer in a quasi-two-dimensional Bi2O2Se crystal. \textit{Physical Review Materials}. American Physical Society, 2025, vol.~9, No~5, p.~1-10. ISSN~2475-9953. Available from: https://doi.org/10.1103/PhysRevMaterials.9.054603.

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