Enhanced deposition rate of lithium phosphorus oxynitride thin films by sputtering of Li3PO4 in N2–He gas mixtures

The addition of He to N2 increases significantly the deposition rate of lithium phosphorus oxynitride thin films by radio frequency magnetron sputtering of Li3PO4 targets. From the correlation with the optical emission intensity, the enhanced rate is attributed to an increase in the N+2 ion concentration in the plasma due to Penning ionization. The ionic conductivity of the films deposited at higher rates in He+20% N2 compares favorably with that of films deposited at lower rates in pure N2.