Study of Nanoparticles Formation in a Pulsed Magnetron Discharge in Acetylene

Abstract

The aim of this work is to study in a pulsed magnetron discharge of acetylene at 10−1 Torr, the influence of tOFF parameter on roughness and morphology of films deposited on silicon substrates. By using a low power discharge (long tOFF and short tON for a given power), a coating with unique morphology is deposited. This film is formed of nanoparticles and particular agglomerates called ‘flowers’ of micrometric size. To the best of our knowledge, it's the first time that such ‘flowers’ structures have been observed for a pulsed plasma polymerization of acetylene. According to the obtained results in mass spectrometry of plasma, nanoparticles and ‘flowers’ are probably formed in gas phase. A growth mechanism in several steps is proposed.

Laser desorption/ionization fourier transform mass spectrometry of thin films deposited on silicon by plasma polymerization of acetylene

“…Moreover, in the material science field, nanoparticles can be used to obtain a rough surface that increases the hydrophobic properties of film. Previous work showed that plas-mas, which generate nano-or micrometer-sized particles, can lead to the formation of novel interesting surfaces called nano-or microflowers [14]. To the best of our knowledge, this is the first time that such structure was observed for plasma polymerization of acetylene.…”

“…SEM pictures of some BP films (Figure 4) showed the presence of spherical structures ("nanoparticles") and unique, particular structures called "flowers" [25]. It can be seen from Table 1 that some UP or DC thin films have rough surfaces but this roughness is not caused by "nanoparticles" or "flowers" formation.…”

“…The films produced in these conditions had smooth surfaces and the corresponding LDI-FTMS spectra showed only carbon cluster signals for positive ion mode and both hydrocarbon and carbon cluster signals (with much higher relative intensity of carbon cluster signals) in negative ion mode. Alternatively, when bipolar pulsed discharge was employed at 5 ϫ 10 Ϫ1 Torr with a high acetylene gas flow (375 cm 3 /min) during a certain time (Ͼ10 min), the quadrupole mass spectra of the plasma constituents showed signals corresponding to polycyclic aromatic hydrocarbons (PAHs) with m/z higher than 100 (Figure 4, bottom row) [25]. The films formed using these conditions had "nanoparticles" and "flowers" on their surface.…”

“…Thin films were deposited on silicon substrates with the deposition parameters given in Table 1. The vacuum chamber for film deposition is described elsewhere [25]. A differentially pumped quadrupole mass spectrometer (Hiden PSM, Warrington, UK) was part of the deposition system for plasma polymerization and was used to analyze the plasma in the early stages of polymerization.…”

Nanostructured plasma polymers

“…Nanostructured coatings were also deposited on Si(100) substrates in pulsed magnetron discharges using acetylene (C 2 H 2 ) as a precursor [108][109][110]. A DC power supply was modulated with different frequencies varying from 7 to 33 kHz.…”