Self-consistent dc glow-discharge simulations applied to diamond film deposition reactors

Self-consistent particle-fluid hybrid simulations have been used to study the structure of hydrogen dc discharges between parallel plates. A Monte Carlo simulation is used to describe individual energetic electrons in the cathode sheath, while the electrons and ions in the low-field region of the discharge are modeled as a fluid. Simulation results for pure H₂ discharges at conditions typical in diamond growth (approximately 20-30 Torr at 1000 K, 100-200 A m^-2) are in reasonable agreement with optical emission and Langmuir probe measurements. The space potential in these discharges is negative with respect to the anode, unlike comparable discharges at lower pressures. Anode glows are predicted by the simulation and are observed experimentally. Dissociation of H₂ in the anode region contributes significantly to the flux of atomic hydrogen to the anode, where diamond is typically grown.