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Electrostatic assembly of alumina nanoparticles on nanocrystalline diamond films
Verveniotis, Elisseos ; Kromka, Alexander ; Rezek, Bohuslav
We apply atomic force microscope for local electrostatic charging of oxygen-terminated nanocrystalline diamond (NCD) thin films deposited on silicon, to induce electrostatically driven self-assembly of colloidal alumina nanoparticles into micro-patterns. The NCD films have sub-100 nm thickness and 60% relative sp2 phase content. We characterize charge contrast and stability in air, fluorocarbon oil and water by Kelvin force microscopy. We discuss factors influencing the charging process and demonstrate that the contrast of more than ± 1 V is needed to induce selfassembly of the nanoparticles via coulombic and polarization forces.
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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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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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