Self-organized subwavelength ripple by nanosecond laser induced chemical vapor deposition

• Polymeric α-C:H thin films prepared by laser induced CVD with the laser wavelength of 248 nm
• Fine ripples with periodicities of about 200 nm observed on the surface of the films
• Composition and chemical bonds studied by Raman and Fourier transform infrared spectroscopy

Polymeric hydrogenated amorphous carbon (α-C:H) thin films were prepared by laser induced chemical vapor deposited method using a KrF excimer laser (λ = 248 nm, ґfwhm = 25 ns) with different laser intensities. Field emission scanning electron microscopy and atomic force microscopy were used to investigate the surface morphology of the films. It was found that the surface morphologies were affected by the laser intensity significantly. Self-organized subwavelength fine ripples perpendicular to the laser beam polarization with periodicities of about 200 nm were observed and a reasonable explanation was proposed for the formation of the ripples. Raman spectroscopy and Fourier transform infrared spectroscopy were used to study the structure of the α-C:H films. The results suggested that there was oxygen in the films, which came from the ambient contamination and the incomposited impurities during and after deposition. The relationships between the composition and chemical bond types were discussed in detail.