Figure 5

Sputtering parameters. a) growth rate γ as function of nitrogen flow \(J_{N_{2}}\) at different back-ground pressures \(\rho _{\mathrm{bg}}\) and plasma power P. b) dc voltage \(V_{\mathrm{dc}}\) between plasma source and target as function of \(J_{N_{2}}\) for two valued of \(\rho _{\mathrm{bg}}\) and P. A kink in the curve is obersed in both a) and b) at the same values of \(J_{N_{2}}\). This kink corresponds to sputtering at a stoichiometric ratio. c) growth rate γ as a function of background pressure \(\rho _{\mathrm{bg}}\) showing a monotonous decay as lower \(\rho _{\mathrm{bg}}\) correspond to larger mean-free paths and therefore to a smaller scattering of the sputtered material. d) dc voltage \(V_{\mathrm{dc}}\) between the plasma source and the target as a function of background pressure \(\rho _{\mathrm{bg}}\). When lowering \(\rho _{\mathrm{bg}}<2\) mTorr, \(V_{\mathrm{dc}}\) increases drastically and the plasma becomes unstable. All traces were measured at a fixed argon flow rate \(Q_{\mathrm{Ar}}=50\) sccm