Reactive pulsed laser deposition of silica and doped silica thin films

Silicon oxide and Si-, GeO2-, B2O3- and P2O5-doped SiO2 films were deposited under various conditions by pulsed laser deposition using a KrF (248 nm wavelength) excimer laser, and were characterized by profilometry, ellipsometry and Rutherford backscattering. Relationships between laser energy, repetition rate, substrate temperature and oxygen pressure, and the composition, optical properties and roughness of the films were examined. SiO2 deposited from a Si target at a substrate temperature of 400 deg. C, oxygen pressure of approximately 6 Pa, laser energy of 550 mJ/pulse, and laser repetition rate of 25 Hz had a composition and refractive index close to the bulk values. Doped silica was made by ablation from sintered mixed oxide targets. Germanium and phosphorus doping increased the refractive index as compared to pure SiO2, but boron doping decreased the refractive index