Optical emission spectroscopy on Ar/N/sub 2/ and Ar/N/sub 2//C/sub 2/H/sub 2/ expanding thermal plasmas

This work has been carried out in connection with the possibilities to deposit carbon nitride materials by expansion thermal plasma assisted chemical vapour deposition (ETP-A-CVD). With the same technique high deposition rates and good quality a-Si:H and a-C:H materials have been obtained. A study of the intensity of atomic lines and molecular bands in a Ar/N/sub 2/ and Ar/N/sub 2//C/sub 2/H/sub 2/ expanding thermal plasma has been performed. In the case of the Ar/N/sub 2//C/sub 2/H/sub 2/ mixture rotational and vibrational temperatures were obtained by comparing computer simulated spectra of the CN(B/sup 2/ Sigma -X/sup 2/ Sigma , Delta v=0) spectral system bands with the experimental spectra. The CN ground state density is determined by taking into account the self-absorption of the CN band

Argon ion-induced dissociation of acetylene in an expanding Ar/C2H2 plasma

Mass spectrometric and Langmuir probe measurements reveal that the plasma chemistry of an expanding Ar/C2H2 plasma which is used for deposition of hydrogenated amorphous carbon is dominated by argon ion-induced dissociation of the precursor gas. The ion-induced dissociation is very efficient leading to complete depletion under certain conditions. The ion fluence as determined from modeling the mass spectrometry results is in good agreement with Langmuir probe measurements suggesting a one-to-one relation between the argon ion and acetylene consumption. The good correlation found between the growth rate and the acetylene consumption rate expresses the efficient use of the dissociation products. © 1999 American Institute of Physics. © 1999 American Institute of Physic

Anomalous fast recombination in hydrogen plasmas involving rovibrational excitation

Langmuir-probe measurements in a hydrogen-containing plasma jet show anomalous fast recombination that cannot be attributed to atomic processes such as radiative or three-particle recombination. In this paper a molecular mechanism, based on the charge transfer between the atomic hydrogen ions and the rovibrationally excited hydrogen molecules (H/sub 2//sup nu ,J/+H/sup +/ to H/sub 2//sup +/+H), is presented that explains the observed fast recombinatio

Active actinometry on a cold hydrogen afterglow

Summary form only given. A new method of actinometry has developed to characterize the cold afterglow of an expanding thermal plasma source in hydrogen. A small electrode is placed in the afterglow to generate a local low-frequency (100-500 kHz) plasma. In this plasma fast electrons are created that can excite particles from the ground state to visible light emitting levels. The atomic Balmer alpha line and the molecular Fulcher band are used to determine the atomic and molecular abundances of the plasma. The power input from the low frequency discharge is kept low enough to assure that the plasma composition and the gas temperature are not significantly influenced. Active actinometry thus offers a method to sample the composition and the ground state molecular populations of the flowing afterglow plasma. The method has been successfully applied under plasma conditions with a low electron temperature (<0.2 eV) and a low electron density (<10/sup 17/ m/sup -3/