Using direct-current anode bias in an S-Gun magnetron sputtering system during the reactive deposition of Al2O3 increases the index of refraction from 1.52 to 1.70. This effect takes place at less than 75% of the 02 flow rate necessary to convert the sputter cathode from the metal mode to the oxide mode. A second effect of sputtering in the linear portion before the "knee" of the voltage versus 02 flow rate curve (hysteresis curve) is a stable and noise-free deposition.