Buckling instability in amorphous carbon films

Zhu, X. D.*; Narumi, Kazumasa; Naramoto, Hiroshi*

In this paper, we report the buckling instability in amorphous carbon films on mirror-polished sapphire (0001) wafers deposited by ion beam assisted deposition at various growth temperatures. For the films deposited at 150C, many interesting stress relief patterns are found, which include networks, blisters, sinusoidal patterns with -shape, and highly ordered sinusoidal waves on a large scale. Starting at irregular buckling in the centre, the latter propagate towards the outer buckling region. The maximum length of these ordered patterns reaches 396 m with a height of 500 nm and a wavelength of 8.2 m. However, the length decreases dramatically to 70 m as the deposition temperature is increased to 550C. The delamination of the film appears instead of sinusoidal waves with a further increase of the deposition temperature. This experimental observation is correlated with the theoretic work of Crosby (1999 Phys. Rev. E 59 R2542).