@PhDThesis{Miranda:2009:FiDiNa,
author = "Miranda, Cl{\'a}udia Renata Borges",
title = "Filmes de diamante nanocristalino infiltrados em substratos de
sil{\'{\i}}cio poroso atrav{\'e}s das t{\'e}cnicas CVD/CVI",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2009",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2009-03-12",
keywords = "diamante nanocristalino, sil{\'{\i}}cio poroso, filmes finos,
deposi{\c{c}}{\~a}o qu{\'{\i}}mica a partir da fase vapor
assistida por filamento quente (HFCVD), infiltra{\c{c}}{\~a}o
qu{\'{\i}}mica a partir da fase vapor assistida por filamento
quente (HFCVI), nanocrystalline diamond, porous silicon, thin
films, hot filament chemical vapor deposition (HFCVD), hot
filament chemical vapor infiltration (HFCVI).",
abstract = "O crescimento de filmes de diamante nanocristalino (NCD -
Nanocrystalline Diamond) obtido atrav{\'e}s da
infiltra{\c{c}}{\~a}o nos poros do sil{\'{\i}}cio poroso (PS -
Porous Silicon) foi estudado utilizando microscopia
eletr{\^o}nica de alta resolu{\c{c}}{\~a}o,
difra{\c{c}}{\~a}o de raios-x de alta resolu{\c{c}}{\~a}o,
espectroscopia de fotoel{\'e}trons de raios-x e espectroscopia de
espalhamento Raman. Os filmes de NCD/PS resultaram em um material
comp{\'o}sito, com grande potencial de aplica{\c{c}}{\~a}o
eletroqu{\'{\i}}mica, principalmente devida {\`a} sua grande
{\'a}rea supercial ativa. Utilizando o processo de
anodiza{\c{c}}{\~a}o com {\'a}cido fluor{\'{\i}}drico e
acetonitrila foram produzidas camadas de PS com poros em
microescala, do tipo pir{\^a}mide invertida, adequados para a
deposi{\c{c}}{\~a}o e infiltra{\c{c}}{\~a}o dos filmes NCD.
Para otimizar o processo de crescimento o reator de
deposi{\c{c}}{\~a}o qu{\'{\i}}mica a partir da fase vapor
(HFCVD - Hot Filament Chemical Vapor Deposition) foi adaptado para
um reator de infiltra{\c{c}}{\~a}o qu{\'{\i}}mica a partir da
fase vapor (HFCVI - Hot Filament Chemical Vapor Infiltration).
Este procedimento permitiu que os gases reagentes infiltrassem na
estrutura porosa onde a nuclea{\c{c}}{\~a}o {\'e} iniciada,
seguida da coalesc{\^e}ncia e forma{\c{c}}{\~a}o do filme tanto
nas paredes como no fundo dos poros. Nesta
configura{\c{c}}{\~a}o uma entrada adicional de CH4 foi
posicionada pr{\'o}xima ao PS que permitiu mudar a
posi{\c{c}}{\~a}o do fluxo em rela{\c{c}}{\~a}o {\`a} amostra
e possibilitou a utiliza{\c{c}}{\~a}o do fluxo adicional
exatamente abaixo da amostra ou acima desta, por{\'e}m ambas as
entradas foram abaixo dos filamentos. Este sistema permitiu ainda
combina{\c{c}}{\~o}es na varia{\c{c}}{\~a}o das
concentra{\c{c}}{\~o}es de CH4 nas duas entradas no intervalo
entre 0,5 e 1,0 vol %. Os filmes obtidos com entrada de g{\'a}s
acima da amostra apresentaram as melhores caracter{\'{\i}}sticas
de NCD em todo o intervalo de varia{\c{c}}{\~a}o de metano
estudado. Numa segunda configura{\c{c}}{\~a}o, para melhorar a
infiltra{\c{c}}{\~a}o do NCD no PS foi utilizado carbono
v{\'{\i}}treo reticulado (CVR) como fonte adicional de carbono.
Nestes experimentos, enquanto o fluxo principal de metano variou
entre 0 e 1,0 vol. %, foram utilizados CVR obtidos com tr{\^e}s
{\'{\i}}ndices de grafitiza{\c{c}}{\~a}o diferentes, tratados
termicamente em 1300, 1500 e 2000ºC. A amostra de PS foi
posicionada sobre o CVR permitindo que o hidrog{\^e}nio
at{\^o}mico atacasse a superf{\'{\i}}cie do mesmo durante o
processo de crescimento do filme, retirando desta estrutura o
carbono que participa das rea{\c{c}}{\~o}es de crescimento do
NCD. Foi observada uma forte depend{\^e}ncia no crescimento do
filme em fun{\c{c}}{\~a}o do CVR utilizado, devido {\`a}s
varia{\c{c}}{\~o}es das propriedades
f{\'{\i}}sico-qu{\'{\i}}micas deste material com sua
temperatura de obten{\c{c}}{\~a}o. Particularmente, os filmes
obtidos a partir do CRV 2000 e concentra{\c{c}}{\~a}o de metano
de 1,0 vol. % apresentaram a melhor morfologia com cobertura total
das paredes e dos poros, seguindo a morfologia do substrato, cuja
qualidade e cristalinidade foram confirmadas pelos espectros Raman
e de raios-x, respectivamente. De maneira geral, as duas
configura{\c{c}}{\~o}es utilizando fontes adicionais de carbono
produziram com sucesso filmes de NCD infiltrados nos poros do Si
com apenas 60 min de crescimento. ABSTRACT: The growth of
nanocrystalline diamond films (NCD) on porous silicon (PS)
substrate was studied using high resolution scanning electron
microscopy, high resolution X-ray diffraction, X-ray photoelectron
spectroscopy and Raman scattering spectroscopy. The NCD/PS films
resulted in a composite material, with great potential for
electrochemical application, mainly due to its high active surface
area. The morphology of PS pores in microscale, which looks like
an inverted pyramid, was produced in a suitable way for the
deposition and infiltration of NCD films, from anodization
process, using the solution of fluoridric acid dissolved in
acetonitrile additive. To optimize the process a Hot Filament
Chemical Vapor Deposition reactor was changed for a Hot Filament
Chemical Vapor Infiltration reactor. This procedure allowed the
infiltration of the reacting gases into the porous structure where
the nucleation takes place, followed by the coalescence and the
film formation into pore bottoms and walls. In this configuration
an additional entrance of CH4 was located next to the PS substrate
using two distinct positions. These positions concerned the NCD
films obtained with the use of the additional flow accurately
underneath of the sample or above it, nonetheless both entrance
were located below the filaments. This system still allowed
combinations in CH4 concentrations for the two entrances in the
range between 0.5 and 1.0 vol %. The films produced using the
above gas entrance, presented the best NCD characteristics, in the
whole range of methane variation. In the second configuration, to
improve the NCD infiltration in the PS substrate, a piece of
reticulated vitreous carbon (RVC) was used as an additional carbon
source. In these experiments, while the main methane flow varied
between 0 and 1.0 vol. %, RVC produced at three different
graphitization index, treated thermally at 1300, 1500 and 2000 ºC,
were used as a second carbon source. The PS sample was placed in
the center of RVC piece allowing the atomic hydrogen attack on its
surface during the film growth, removing from its structure the
necessary carbon to promote the reactions to form the NCD layer.
The strong dependence in the film growth as a function of the RVC
treated at different temperatures was observed, due to the
physical-chemical property variations of this material with its
graphitization index. Particularly, the films obtained from the
RVC-2000 and 1.0 vol. % of methane concentration presented the
best morphology with a continuous NCD film covering the pore wall
and bottom following the substrate morphology, with high quality
and crystallinity, confirmed from its Raman and X-ray spectra,
respectively. In general, the two used configurations for
additional carbon sources provided NCD film infiltration in PS
substrate with success for only 60 min of growth time.",
committee = "Baldan, Maur{\'{\i}}cio Ribeiro (presidente) and Ferreira,
Neiden{\^e}i Gomes (orientador) and Beloto, Antonio Fernando
(orientador) and Ueda, Mario and Rezende, Mirabel Cerqueira and
Silva, Leide Lili Gon{\c{c}}alves da",
copyholder = "SID/SCD",
englishtitle = "Nanocrystalline diamond films infiltrates in porous silicon
substrate by CVD/CVI Processes",
language = "pt",
pages = "189",
ibi = "8JMKD3MGP8W/354ETLP",
url = "http://urlib.net/ibi/8JMKD3MGP8W/354ETLP",
targetfile = "publicacao.pdf",
urlaccessdate = "07 maio 2024"
}