Spectroscopy and Optical Properties of Novel Metal(II)-Azo Complex Films in Blue-Violet Light Region

A novel azo derivative, α-(2-azoxyisoxazole)-β-diketone derivative (ADD), and its copper (II) and nickel (II) complex (CuADD and NiADD) films have been prepared respectively by spin-coated method. The absorption spectra of the films on a K9 glass substrate in the 300-800 nm wavelength region have been measured. The optical constants (complex refractive index N = n+ik) and thickness of the complex films on a single-crystal silicon substrate in the 300-600 nm wavelength region have been investigated on an improved rotating analyzer-polarizer (RAP) type of scanning ellipsometer, and the dielectric constants ε (ε = ε₁ + iε₂), absorption coefficients α as well as reflectance R of the films were calculated. It is found that the absorption maxima of the ADD, CuADD and NiADD films are at 324 nm, 372 nm and 385 nm, respectively, and small absorption values and steep absorption band edges of the CuADD and NiADD films are observed at the 405 nm side, the CuADD and NiADD films give high n values of 2.08 and 1.98, and low k values of 0.2 and 0.28, respectively, at 405 nm, and their thicknesses in the range of 130-150 nm, the high reflectivity of 58.5% and 45.5% of the CuADD and NiADD films with Ag as a reflective layer were obtained at the film thicknesses of 70 nm and 80 nm respectively. These results show that the novel CuADD and NiADD films seem to be a very promising organic recording material for next generation of high density digital versatile disc-recordable (HD-DVD-R) systems that use a high numerical aperture of 0.85 at 405 nm wavelength.