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Důležitost vlivu nukleační fáze na vlastnosti nanokrystalických diamantových vrstev připraveným metodou PECVD
Zajíčková, L. ; Karásková, M. ; Jašek, O. ; Buršíková, V. ; Franta, D. ; Matějková, Jiřina ; Klapetek, P.
Microcrystalline diamond finds several applications due to its high hardness but also as electronic and optical devices. However, its roughness makes some applications like tribology, emission cathodes for flat panel displays, optical coatings and emerging Nano/Micro-Electro-Mechanical Systems (N/MEMS) difficult. A major advance was achieved in early 90ties when the crystalline size was decreased from down to nanometers. However, the processes leading to the deposition of small grain-sized diamond films are not yet properly understood and these films exhibit different properties and morphology depending on the method of preparation. Therefore, the nanocrystalline diamond (NCD) covers very different materials such as columnary grown films with the grain sizes usually quoted below 100 nm (but 30 nm are nowadays possible)and continuous dense coatings with grain sizes reaching 5-15 nm grown under high re-nucleation rates.
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Depozice a zpracování uhlíkových nanotrubek připravených metodou PECVD za atmosférického tlaku
Kučerová, Z. ; Zajíčková, L. ; Jašek, O. ; Eliáš, M. ; Synek, P. ; Matějková, Jiřina ; Rek, Antonín ; Buršík, Jiří
Carbon nanotubes (CNTs) were synthesized by plasma enhanced chemical vapor deposition from mixture of argon, methane and hydrogen using microwave plasma torch at atmospheric pressure. Nanotubes grew on a complex substrate system consisting of silicon wafer, buffer layer and thin catalytic iron film. As confirmed by scanning electron microscopy (SEM), this deposition technique produces bundles or ropes of nanotubes covered by crust composed of catalytic particles, amorphous carbon and other impurities such as fullerenes or other carbon nanoparticles. Because many scientific and technological applications, as well as characterization techniques require individual nanotubes a great attention has to be paid to the post-deposition processing of the deposit. The nanotube bundle could be separated by ultrasonication of the deposit in organic or inorganic liquid. Most commonly used liquids are water or ethanol.
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Depozice uhlíkových nanotrubek metodou depozice z plynné fáze s asistencí plazmatu
Jašek, O. ; Eliáš, M. ; Zajíčková, L. ; Kučerová, Z. ; Kudrle, V. ; Matějková, Jiřina ; Rek, Antonín ; Buršík, Jiří
Carbon nanotube properties provoked interest in many fields of application but there is still need to develop deposition techniques, which enable precise control of nanotubes positioning, alignment and properties. Chemical vapor deposition (CVD) methods and lately also plasma enhanced CVD (PECVD) are most promising to reach this goal. In the first part of the article we will briefly describe carbon nanotubes structure and properties and review the necessary conditions and possible control mechanisms used in PECVD deposition method. In the second part, examples of two deposition techniques, one working at a low pressure and one at an atmospheric pressure, will be described and reached results analyzed.
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Nanocrystalline diamond films deposition by PECVD in ASTEX type microwave reactor
Jašek, O. ; Karásková, M. ; Buršíková, V. ; Zajíčková, L. ; Franta, D. ; Frgala, Z. ; Matějková, Jiřina ; Rek, Antonín ; Klapetek, P. ; Buršík, Jiří
Nanocrystalline diamond film was deposited by microwave CVD in the ASTeX type reactor on a mirror polished (111) oriented n-doped silicon substrate. The deposition mixture consisted of 9 pct of methane in hydrogen. The applied microwave power (2.45 GHz)and pressure were 850 W and 7.5 kPa, respectively. The substrate temperature was 1 090 K. The diamond nucleation process was enhanced by rf induced dc selfbias of -125 V. The film exhibited very low roughness (rms of heights 9.1 nm). Its hardness and elastic modules were 70 and 375 GPa, respectively. The optical constants were determined by combination of spectroscopic ellipsometry and reflectometry employing the Rayleigh-Rice theory for the roughness and the dispersion model of optical constants based on the parameterization of densities of states. The deposition rate was 57 nm/min including the 5 min nucleation step.
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Mechanical properties of nanocrystaline diamond thin films
Buršíková, V. ; Frgala, Z. ; Jašek, O. ; Karásková, M. ; Zajíčková, L. ; Franta, D. ; Buršík, Jiří ; Klapetek, P. ; Bláhová, O. ; Matějková, Jiřina
Mechanical properties of nanocrystaline diamond films.
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