Zirconia-ormosil films doped with PbS quantum dots

Zirconia-ormosil (organically modified silicates) films doped with differen t concentrations of PbS quantum dots were synthesized by sol-gel processing . A sol containing 3-(trimethoxysilil)propylmethacrylate as matrix precurso r was mixed with a PbS colloidal doping sol. The control of the particle si ze was obtained by using 3-mercaptopropyltrimethoxysilane as capping agent in the PbS colloidal sol, The microstructure of the films was investigated by Fourier transform infrared spectroscopy, Rutherford backscattering spect rometry, X-ray diffraction and high resolution transmission electron micros copy. Linear and non-linear optical properties were studied by absorption s pectrophotometery and non-linear m-line technique, A curing temperature of 130 degrees C allowed a good degree of densification without deterioration of the sulfide particles and the change in refractive index from the substr ate was sufficient to support waveguide modes. The doping concentration aff ected the mean particle size, shifting the linear absorption to shorter wav elengths for films doped with a smaller amount of PbS, The non-linear refra ctive index nz was measured at 1.064 mu m. A negative and fully reversible non-linear effect was measured, with nz values in the range 10(-15)-10(-16) m(2)/W, depending on the concentration of PbS quantum dots. (C) 1999 Elsev ier Science B.V. All rights reserved.