Single crystal growth of monoisotopic hexagonal boron nitride from a Fe-Cr flux

Hexagonal boron nitride (hBN) is an important insulator that is incorporated into numerous 2D electronic, optoelectronic, and photonic devices, whereas natural hBN is a mixture of 20% 10 B and 80% 11 B isotopes, and monoisotopic hBN is a variant with just a single boron isotope, either 10 B or 11 B....

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2020-01, Vol.8 (29), p.9931-9935
Main Authors: Li, Jiahan, Elias, Christine, Ye, Gaihua, Evans, Dylan, Liu, Song, He, Rui, Cassabois, Guillaume, Gil, Bernard, Valvin, Pierre, Liu, Bin, Edgar, James H
Format: Article
Language:English
Subjects:
Boron
Boron nitride
Chromium
Crystal growth
Crystals
Electronic devices
Iron
Neutron absorption
Neutron counters
Neutron flux
Optoelectronic devices
Phonons
Photoluminescence
Polaritons
Single crystals
Thermal conductivity
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Summary:Hexagonal boron nitride (hBN) is an important insulator that is incorporated into numerous 2D electronic, optoelectronic, and photonic devices, whereas natural hBN is a mixture of 20% 10 B and 80% 11 B isotopes, and monoisotopic hBN is a variant with just a single boron isotope, either 10 B or 11 B. Consequently, monoisotopic hBN has a higher thermal conductivity and a stronger neutron absorption (in the case of h 10 BN), making it superior for neutron detectors, heat management materials in nano flexible electronic devices, and phonon polariton-based nanophotonics. Here we synthesized approximately monoisotopic hBN using boron powder containing a single boron isotope and nitrogen, and grew single crystals from a Fe-Cr metal flux at atmospheric pressure. Narrow Raman peaks from the shear (≤1.3 cm −1 ) and intralayer (≤3.3 cm −1 ) modes demonstrate that the crystals are highly ordered. In the photoluminescence spectra, the presence of phonon-assistant transition peaks is also indicative of the high-quality of the crystals. This growth protocol permits us to get rid of the emission at 4.1 eV. This work provides a novel material for studying the fundamental properties of isotopic effects and the high-performance hBN device. High-quality monoisotopic hBN were synthesized using Fe-Cr flux. Boron and nitrogen were dissolved at a high temperature, then hBN single crystals were precipitated during cooling process.
ISSN:2050-7526
2050-7534
DOI:10.1039/d0tc02143a