Optical properties of nickel(II)–azo complexes thin films for potential application as high-density recordable optical recording media

Smooth thin films of three kinds of nickel(II)–azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrate in the 300–600 nm wavelength region were measured. Optical constants (complex refractive index N = n + i k ) and thickness of the thin films prepared on single-crystal silicon substrate in the 300–600 nm wavelength region were investigated on rotating analyzer–polarizer type of scanning ellipsometer, and dielectric constants ε ( ε = ε 1 + i ε 2 ) , absorption coefficients α as well as reflectance R of thin films were then calculated at 405 nm. In addition, in order to examine the possible use of nickel(II)–azo complex thin film as an optical recording medium, one of the nickel(II)–azo complex thin film prepared on K9 glass substrate with an Ag reflective layer was also studied by atomic force microscopy and static optical recording. The results show that the nickel(II)–azo complex thin film is smooth and has a root mean square surface roughness of 2.25 nm, and the recording marks on the nickel(II)–azo complex thin film are very clear and circular, and their size can reach 200 nm or less.