Acetylene (ethyne) C2H2
C2H2 for diamond films by cyclic growth/etch oxy-acetylene CVD process
Acetylene C2H2 has been applied for the deposition of diamond thin films on tungsten substrate by a cyclic growth/etch oxy-acetylene process. The presence of 8H polytype of diamond was confirmed by Raman spectroscopy. Different phases of tungsten carbide were formed on the W substrate/diamond film interface, as determined by XRD.[[i] ]
Acetylene C2H2 for GeCx films by X-Ray activated CVD
Acetylene (ethyne) C2H2 (in combination with germane GeH4 as co-reactant) has been applied as carbon precursor for the growth of GeCx films by X-Ray activated CVD. The molar ratio C2H2/GeH4 was varied to determine the factors leading to the highest yields of solid products and of obtaining information on the main ionic and radical reaction paths giving the amorphous material. For this purpose, samples were X-Ray irradiated and qualitative and quantitative GC/MS analyses of the volatile products, as well as the determination of the solid composition was performed. The ion/molecule reactions have been studied by ion trap mass spectrometry, determining the ionic reaction mechanisms and the rate constants of the most significant processes. It was determined that two main and opposite factors affect the formation of the amorphous product: (a) the excess of C2H2 with respect to germane favors both radical and ionic decomposition paths; (b) the increase of C2H2 content in the irradiated mixtures lowers the total number of activated species. Therefore, the best yield of amorphous germanium carbides was obtained when germane and ethyne have a molar ratio between 2/1 and 1/1.[[ii ]
[i] R. Kapil, B.R. Mehta, V.D. Vankar,
[ii] Paola Benzi, Elena Bottizzo, Lorenza Operti, Roberto Rabezzana, G. A. Vaglio, P. Volpe, Chem. Mater., 2002, 14 (6), pp 2506–2513, DOI: 10.1021/cm011261q, “Amorphous Germanium Carbides by Radiolysis−CVD of