The atomic nitrogen (N) ion flux and impacting ion energy are the two important parameters, which influence the performance of production of plasma nitridation applications such as N-doped graphene. In this paper, a novel method is described to control the flux and ion energy of atomic N ion (N+) and molecular N2 ion (N2 +) using a helicon-wave-excited plasma (HWP) with Ar/N2 gas mixtures. It shows that by varying the flow-rate ratio of N2/(N2+Ar) (α ), the ratio of [N+]/[N2 +] ( β ) can be controlled obviously, and β could be increased up to 1.2 at α = 0.5 , which is much higher than that in pure N2 HWP discharge (β ∼ 0.2). The maximum density and flux of atomic N+ are obtained, which are 2.5× 1018 m-3 and 8.6 × 1021, m-2s-1, respectively. The results show that the addition of Ar into N2 plasma can be employed to remarkably increase the [N+]/[N2 +] due to electron-impact ionization involving the metastable state of Ar. The N+ ion beams are formed with a speed near to Mach 3, and the ion-beam energy is increased from 30 to 50 eV with increasing α to 0.75.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics