Low loss Nb2O5 films deposited by novel remote plasma sputtering

We report the deposition of Nb₂O₅ films on unheated BK-7 glass substrates using remote plasma sputtering system. The remote plasma geometry allows pseudo separation of plasma and target bias parameters, which offers complete deposition rate control. Using appropriate oxygen flow rates, high-density and low-loss Nb₂O₅ films are deposited with rates up to 0.49 nm/s. Lower deposition rates (～0.026 nm/s) can also be obtained by working at low target current and voltage and at low pressure. Nb₂O₅ films deposited at different rates have the refractive index of about 2.3 and the extinction coefficient as low as 6.9×10^?5.