Nonlinear optical and ellipsometric study of manganese-phthalocyanine thin films

Abstract

Linear and non-linear optical properties of Manganese-phthalocyanine (MnPc) thin films in the near infrared (NIR) are reported. MnPc thin films are prepared by vapor deposition on glass and the effects of growth conditions on the optical properties are also studied. First, Morphology of the MnPc film is studied using atomic force microscope and the structure of the film is studied using theta-2theta scan X-ray diffraction. The MnPc films consist of grains with sizes of several tens of nanometers. The grain size depends on the substrate temperature of the vapor deposition process. The growth conditions also affect the reflection intensity from the {1 0 0} facet of MnPc. The films are studied using spectroscopic ellipsometry for the NIR region (1200-1800 nm) in wide wavelength range (0.6-6.5 eV) with various incidence angles (60-80°). The nonlinear optical properties of saturable absorption are also studied by the Z-scan method with a CW laser with a wavelength of 1550 nm. The substrate temperature affects Δ and ψ more drastically than the deposition rate and this is most pronounced in the NIR region. From the saturable absorption experiments, the same trend that the substrate temperature drastically affects the nonlinear coefficient of MnPc, was also evident.