Critical view on buffer layer formation and monolayer graphene properties in high-temperature sublimation
(2021) In Applied Sciences (Switzerland) 11(4). p.1-16- Abstract
In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using closed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer graphene on 4H–SiC. We show that by introducing Ar at higher temperatures, TAr, one can shift the formation of the buffer layer to higher temperatures for both n-type and semi-insulating substrates. A scenario explaining the observed suppressed formation of buffer layer at higher TAr is proposed and discussed. Increased TAr is also shown to reduce the sp3 hybridization content and defect densities in the... (More)
In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using closed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer graphene on 4H–SiC. We show that by introducing Ar at higher temperatures, TAr, one can shift the formation of the buffer layer to higher temperatures for both n-type and semi-insulating substrates. A scenario explaining the observed suppressed formation of buffer layer at higher TAr is proposed and discussed. Increased TAr is also shown to reduce the sp3 hybridization content and defect densities in the buffer layer on n-type conductive substrates. Growth on semi-insulating substrates results in ordered buffer layer with significantly improved structural properties, for which TAr plays only a minor role. The free charge density and mobility parameters of monolayer graphene and quasi-freestanding monolayer graphene with different TAr and different environmental treatment conditions are determined by contactless terahertz optical Hall effect. An efficient annealing of donors on and near the SiC surface is suggested to take place for intrinsic monolayer graphene grown at 2000◦C, and which is found to be independent of TAr . Higher TAr leads to higher free charge carrier mobility parameters in both intrinsically n-type and ambient p-type doped monolayer graphene. TAr is also found to have a profound effect on the free hole parameters of quasi-freestanding monolayer graphene. These findings are discussed in view of interface and buffer layer properties in order to construct a comprehensive picture of high-temperature sublimation growth and provide guidance for growth parameters optimization depending on the targeted graphene application.
(Less)
- author
- Stanishev, Vallery ; Armakavicius, Nerijus ; Bouhafs, Chamseddine ; Coletti, Camilla ; Kühne, Philipp ; Ivanov, Ivan G. ; Zakharov, Alexei A. LU ; Yakimova, Rositsa and Darakchieva, Vanya LU
- organization
- publishing date
- 2021-02-02
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Buffer layer, Epitaxial graphene on SiC, Free charge carrier properties, High-temperature sublimation, Monolayer graphene, Quasi-free-standing graphene, Terahertz optical Hall effect
- in
- Applied Sciences (Switzerland)
- volume
- 11
- issue
- 4
- article number
- 1891
- pages
- 16 pages
- publisher
- MDPI AG
- external identifiers
-
- scopus:85101925276
- ISSN
- 2076-3417
- DOI
- 10.3390/app11041891
- language
- English
- LU publication?
- yes
- id
- 0332db52-1e35-4c7e-8100-cc22c7d9c5a5
- date added to LUP
- 2022-03-22 15:29:18
- date last changed
- 2022-04-22 20:09:33
@article{0332db52-1e35-4c7e-8100-cc22c7d9c5a5,
abstract = {{<p>In this work we have critically reviewed the processes in high-temperature sublimation growth of graphene in Ar atmosphere using closed graphite crucible. Special focus is put on buffer layer formation and free charge carrier properties of monolayer graphene and quasi-freestanding monolayer graphene on 4H–SiC. We show that by introducing Ar at higher temperatures, T<sub>Ar</sub>, one can shift the formation of the buffer layer to higher temperatures for both n-type and semi-insulating substrates. A scenario explaining the observed suppressed formation of buffer layer at higher T<sub>Ar</sub> is proposed and discussed. Increased T<sub>Ar</sub> is also shown to reduce the sp<sup>3</sup> hybridization content and defect densities in the buffer layer on n-type conductive substrates. Growth on semi-insulating substrates results in ordered buffer layer with significantly improved structural properties, for which T<sub>Ar</sub> plays only a minor role. The free charge density and mobility parameters of monolayer graphene and quasi-freestanding monolayer graphene with different T<sub>Ar</sub> and different environmental treatment conditions are determined by contactless terahertz optical Hall effect. An efficient annealing of donors on and near the SiC surface is suggested to take place for intrinsic monolayer graphene grown at 2000<sup>◦</sup>C, and which is found to be independent of T<sub>Ar</sub> . Higher T<sub>Ar</sub> leads to higher free charge carrier mobility parameters in both intrinsically n-type and ambient p-type doped monolayer graphene. T<sub>Ar</sub> is also found to have a profound effect on the free hole parameters of quasi-freestanding monolayer graphene. These findings are discussed in view of interface and buffer layer properties in order to construct a comprehensive picture of high-temperature sublimation growth and provide guidance for growth parameters optimization depending on the targeted graphene application.</p>}},
author = {{Stanishev, Vallery and Armakavicius, Nerijus and Bouhafs, Chamseddine and Coletti, Camilla and Kühne, Philipp and Ivanov, Ivan G. and Zakharov, Alexei A. and Yakimova, Rositsa and Darakchieva, Vanya}},
issn = {{2076-3417}},
keywords = {{Buffer layer; Epitaxial graphene on SiC; Free charge carrier properties; High-temperature sublimation; Monolayer graphene; Quasi-free-standing graphene; Terahertz optical Hall effect}},
language = {{eng}},
month = {{02}},
number = {{4}},
pages = {{1--16}},
publisher = {{MDPI AG}},
series = {{Applied Sciences (Switzerland)}},
title = {{Critical view on buffer layer formation and monolayer graphene properties in high-temperature sublimation}},
url = {{http://dx.doi.org/10.3390/app11041891}},
doi = {{10.3390/app11041891}},
volume = {{11}},
year = {{2021}},
}