It was noted that the addition of He to N2 greatly increased the deposition rate of thin films of this material, Li2.9PO3.3N0.46, when produced by the radio-frequency magnetron sputtering of Li3PO4 targets. On the basis of a correlation with optical emission intensities, the enhanced rates were attributed to an increase in the N2+ ion concentration in the plasma, due to Penning ionization. It was found that the ionic conductivity of films which had been deposited at higher rates in He-20%N2 compared favorably with that of films which had been deposited at lower rates in pure N2. At 25C, the conductivity was equal to 1.3 x 10-6S/cm; as compared with the value of 2.0 x 10-6S/cm for films which had been deposited at a lower rate in pure N2.

J.B.Bates, X.Yu: Journal of Vacuum Science and Technology A, 1996, 14[1], 34-7