BI-12(GAXBI1-X)O-19.5 OPTICAL WAVE-GUIDES GROWN BY PULSED-LASER DEPOSITION

Bi-12(GaxBi1-x)O-19.5 (BGaO) films with thickness in the range 100-100 0 nm have been deposited on (100) Y-stabilized zirconia (YSZ) and (100 ) Bi12GeO20 (BGO) substrates using a KrF excimer pulsed laser and poly crystalline targets with composition x=0.63-0.72. The laser power dens ity threshold for ablation of the targets has been determined to be J( 0)=4.8 J/cm(2). A deposition rate of 0.03 Angstrom/pulse was found for the substrate-target distance (6 cm) and laser fluence (J=7 J/cm(2)) used. Transparent and crystalline films were obtained heating the subs trate in the 450-550 degrees C range under 1.5X10(-1) mbar of oxygen p ressure. Films deposited on hot substrates have a Ga stoichiometry x=0 .5 but a Bi content slightly lower than that corresponding to sillenit e. Films deposited on YSZ show preferential orientation. From the x-ra y diffraction results and the comparison of the ionic distributions, i t has been concluded that the most likely orientation between both lat tices is [310]{130}BGaO parallel to[011]{100}YSZ. A {100}BGaO parallel to{100}BGO epitaxy has been inferred from Rutherford backscattering a nalysis. On both substrates the films behave as step waveguides with r efractive index close to the value determined in bulk BGaO. (C) 1996 A merican Institute of Physics.