PREPARATION OF CRYSTALLINE BETA-BARIUM BORATE (BETA-BAB2O4) THIN-FILMS BY PULSED-LASER DEPOSITION

Crystalline beta barium borate (beta-BaB2O4) thin films have been prepared on silicon (001) and sapphire (001) substrates by the pulsed laser deposition technique. The crystallinity of these films was found to depend sensitively on the deposition temperature. At a deposition temperature around 800 degrees C and in the presence of 75 mTorr of O-2 gas, films grown on Si(100) substrates are typically polycrystalline with x-ray diffraction peaks along (104) and (001) orientations while the film grown on a sapphire (001) substrate is highly textured with (001) orientation (c axis) normal to the film surface. The film grown on sapphire (001) substrate exhibits a maximum effective second harmonic generation coefficient d(eff) of 2.2 pm/V, which is comparable to that of bulk beta-BaB2O4 single crystals. (C) 1995 American Institute of Physics.