PREPARATION AND OPTICAL-PROPERTIES OF GOLD-DISPERSED SRTIO3 THIN-FILMS

Gold-dispersed SrTiO3 thin films were prepared by the r.f. magnetron s puttering method. The as-deposited films were heat-treated in air at t emperatures ranging from 700 to 900 degrees C for 1h. The optical prop erties of the films were compared with those of gold-dispersed BaTiO3 and gold-dispersed SiO2 thin films, which were prepared by the same pr ocedure as gold-dispersed SrTiO3 thin films, The SrTiO3 matrix crystal lized at temperatures above 700 degrees C and fine gold particles beca me coarse between 800 and 900 degrees C, For the SrTiO3 matrix, the pe ak position of the surface plasmon resonance of gold particles shifted toward the longer wavelength as the volume fraction of gold and heat treatment temperature increased, The changes of the absorption peak po sition of the gold-dispersed SrTiO3 thin films were similar to those o f gold-dispersed BaTiO3 thin films. Nonlinear optical property of thes e films was measured by the degenerate four-wave mixing (DFWM) method at 532 nm using a Q-switched Nd: YAG laser with 7-ns pulse duration. T he values of chi((3))/alpha(532) Of the gold-dispersed SrTiO3 thin fil ms were ten times larger than those of the gold-dispersed SiO2 thin fi lms. In the case of SiO2 matrix, enlargement of chi((3))/alpha(532) in accordance with enlargement of particle size of gold originate from a n increase of f(1) due to decreasing epsilon(m)'' Of gold particles. O n the other hand, for the SrTiO3 and BaTiO3 matrices, refractive indic es of the matrices increase with increasing heat treatment temperature . The enlargement of refractive index (n(s)) or dielectric constant (e psilon(f)) Of the films attribute to the enlargement of chi((3))/alpha (532) Of gold-dispersed SrTiO3 and BaTiO3 thin films besides the enlar gement of particle size of gold. In contrast, the nonlinear susceptibi lity of the gold particles, chi m((3)), in the gold-dispersed SrTiO3 a nd BaTiO3 thin films decreased with increasing mean particle size.