Characterization of High-energy electrons by OES in the negative glow

ISOLA, LUCIO M.; LÓPEZ, MAIA M.; GOMÉZ, BERNARDO J.; GUERRA, VASCO; FERREC, A.; DJOUADI A.; JOUAN, P-Y

Nantes

Congreso; 18th International Colloquium on Plasma Processes; 2011

Plasmas generated in Ar-N2 mixtures have been widely studied for different conditions of pressure, N2 percentages, type and discharge zone [1] -[4]. In particular, these plasmas are in great interest because it is the commonly used numerous treatment techniques and generation of thin films and multilayer systems [5,6]. Optical emission spectroscopy (OES) is a non-intrusive and relatively easy-to-use plasma diagnostic, which makes it widely applied to characterize these plasmas, although the spectra interpretation is not straightforward. The absence of Maxwellian electron energy distribution (EEDF) is a frequent complication in the spectral interpretation of the processing plasmas. In particular, the DC negative glow EEDF is strongly non-Maxwellian distribution, it consists of a very small fraction of high-energy electrons generated in the cathode sheath, and of the main body of cold electrons with their temperature close to the room temperature [7]. OES has been used to determine the EEDF non-Maxwellian in different conditions and types of discharges. For instance, in the work [8] of Behringers et. al. the EEDF was determined in the Ar-He-N2 positive column of a stationary DC glow discharge, Vinogradov [9] measuring in positive column of dc glow discharge and electron cyclotron resonance discharge (ECR) in He-N2 and Boffard et. al. [10] measured on the inductively coupled Ar plasma. However, these methods are not directly applied in DC pulsed negative glow. In this work, we have studied the high-energy electrons part of the Ar and Ar-N2 negative glow EEDF, in DC pulsed discharge, through the measure the Ar, Ar+, Ar++ lines and N2, N2+ bands.