Growth of tantalum pentoxide film by pulsed laser deposition

Thin films of Ta2O5 have been deposited on quartz and silicon substrates by 532-nm Nd:YAG.pulsed laser deposition PLD.in various O2 gas environments. The influence of the deposition parameters, such as oxygen pressure, substrate temperature and annealing under UV irradiation using a 172-nm excimer lamp, on the properties of the grown films, has been studied. The refractive index of the films increases with increasing pressure of O2. X-ray diffraction measurements show that the as-deposited films are amorphous at temperatures below 5008C and possess orthorhombic b-Ta2O5.crystal structure at temperatures above 6008C. The optical properties determined by UV spectrophotometry also strongly depend on the deposition parameters. At O2 pressures above 0.15 mbar, the refractive index of the films was about 2.12 which is close to the bulk Ta2O5 value of 2.2. Optical transmittance around 85% in the visible region of the spectrum was obtained at an oxygen pressure of 0.2 mbar. q1999 Elsevier Science B.V. All rights reserved