Effect of Addition of Nitrogen to a Capacitively Radio-Frequency Hydrogen Discharge

A hybrid PIC/MC model is developed in this work for H ₂ -xN ₂ capacitively coupled radio–frequency (CCRF) discharges in which we take into account 43 kinds of collisions reaction processes between charged particles (e ⁻, H⁺₃, H ⁺₂, H ⁺, N⁺₂, N ⁺ ) and ground-state molecules (H ₂ , N ₂ ). In addition, the mean energies and densities of electrons and ions (H + 3, H + 2, H + ), and electric field distributions in the H ₂ -N ₂ CCRF discharge are simulated by this model. Furthermore, the effects of addition of a variable percentage of nitrogen (0-30%) into the H ₂ discharge on the plasma processes and discharge characteristics are studied. It is shown that by increasing the percentage of nitrogen added to the system, the RF sheath thickness will narrow, the sheath electric field will be enhanced, and the mean energy of hydrogen ions impacting the electrodes will be increased. Because the electron impact ionization and dissociative ionization rates increase when N ₂ is added to the system, the electron mean density will increase while the electron mean energy and hydrogen ion density near the electrodes will decrease. This work aims to provide a theoretical basis for experimental studies and technological developments with regard to H ₂ -N ₂ CCRF plasmas.