Pulsed laser deposition of LiNbO3 thin films from Li-rich targets

LiNbO3 thin films were synthesized by pulsed KrF* (lambda=248 nm, tau(FWHM)similar to20 ns, v = 1 Hz) laser ablation of Li-rich ceramic targets on (001) Al2O3 substrates. The crystalline state and composition of the as-grown films were studied by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS) and nuclear reaction analyses (NRA). The laser fluence proved essential for the improvement of the structure and optical properties of the deposited films. The X-ray diffractograms showed that the films consist prevalently of LiNbO3 with preferred (006) orientation, The Li/Nb atomic ratio of about 1.0 was confirmed by the RBS and the NRA results. The ordinary refractive index at 632.8 nm of the film was found to be approximately 2.2, which is close to that of the bulk single-crystalline LiNbO3. The films wave-guide losses measured at the same wavelength were about 18 dB/cm.