Título: | CHEMICAL, STRUCTURAL, TRIBOLOGICAL, AND OPTICAL PROPERTIES OF HEXAGONAL BORON NITRIDE FILMS SYNTHESIZED BY CHEMICAL VAPOR DEPOSITION | ||||||||||||
Autor: |
THAIS CRISTINA VIANA DE CARVALHO |
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Colaborador(es): |
MARCELO EDUARDO HUGUENIN MAIA DA COSTA - Orientador CESAR AUGUSTO DIAZ MENDOZA - Coorientador |
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Catalogação: | 22/AGO/2024 | Língua(s): | ENGLISH - UNITED STATES |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=67676&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=67676&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.67676 | ||||||||||||
Resumo: | |||||||||||||
Hexagonal Boron Nitride (h-BN) is a material composed of alternating
Boron (B) and Nitrogen (N) atoms with a hexagonal aspect. Thin films of
h-BN play a crucial role in the development of applications such as 2D devices
based on Van der Waals heterostructures, protective coatings, tribological applications, among others. The synthesis of h-BN still represents a significant
challenge. In this thesis, the synthesis of h-BN was investigated using the low-pressure chemical vapor deposition (LPCVD) method, employing ammonia
borane (AB) as a precursor source of B and N. The study focused on direct growth on the silicon <100> substrate, thus eliminating the need for film
transfer for subsequent characterization and avoiding degradation and contamination associated with the transfer process. The first part of this study focused
on CVD growth, controlling parameters such as the amount of precursor material, precursor and furnace evaporation temperature, gas flow rates during the
reduction and synthesis stages, temperature, reduction time, synthesis, and
cooling. Two series were synthesized: one as a function of growth temperature
between 1173 and 1373 K, and a second as a function of synthesis time at a
temperature of 1373 K. The films were characterized by spectroscopy, Raman,
Fourier-transform infrared (FTIR), UV-visible (UV-Vis), X-ray photoelectron
(XPS), atomic force microscopy (AFM), contact angle measurements, scanning electron microscopy (SEM), scanning transmission electron microscopy
(STEM), and tribology. Initially, the effect of growth temperature on the quality of films grown for 10 minutes was studied. Raman spectroscopy results
confirmed the growth of h-BN, evidenced by the E2g peak at approximately
1375 cm−1
. Morphological studies showed that temperature variations lead to
the formation of different structures on the Si surface. Growth is observed
from 1273 K, while samples grown below 1223 K show no signs of growth.
We observed the formation of two-dimensional (2D) nanosheets with lateral
dimensions ranging from 80 to 500 nm, as well as the continuous growth of
films with nanocrystals of varying sizes. The B:N ratio determined by XPS was
approximately 1:1, and the optical gap of the h-BN films was determined to be
5.75 eV. Tribology studies demonstrated a friction coefficient of 0.1, and there
was no delamination after 3000 linear reciprocating cycles in the ball-on-disk
test, covering 10 mm in each cycle on the film, while for Si it was 0.6. For
films synthesized as a function of time, Raman spectroscopy characterization
revealed an E2g vibration mode peak at 1374 cm−1 with intensity correlated to
the film thickness. FTIR spectroscopy confirmed the presence of B-N bonds,
and the optical band was determined to be 5.65 eV. Contact angle measurements showed hydrophobic films. XPS data indicated a stoichiometric 1:1 ratio
between B and N, and the thickness was analyzed by cross-sectional STEM
measurements, being around 20 nm for films grown for 10 minutes at 1373 K.
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