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

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378271%3A_____%2F25%3A00627726" target="_blank" >RIV/68378271:_____/25:00627726 - isvavai.cz</a>

Alternative codes found

RIV/00216275:25310/25:39922910 RIV/00216224:14310/25:00141326 RIV/00216208:11320/25:10499663

Result on the web

<a href="https://doi.org/10.1103/PhysRevMaterials.9.054603" target="_blank" >https://doi.org/10.1103/PhysRevMaterials.9.054603</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevMaterials.9.054603" target="_blank" >10.1103/PhysRevMaterials.9.054603</a>

Result language

angličtina

Original language name

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

Original language description

Bi2O2Se 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 εr≈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, k≈T1.5.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Physical Review Materials

ISSN

2475-9953

e-ISSN

2475-9953

Volume of the periodical

9

Issue of the periodical within the volume

5

Country of publishing house

US - UNITED STATES

Number of pages

9

Pages from-to

054603

UT code for WoS article

001495036600002

EID of the result in the Scopus database

2-s2.0-105004739038