Nanobuckling and x-ray photoelectron spectra of carbyne-rich tetrahedral carbon films deposited by femtosecond laser ablation at cryogenic temperatures

作者：Hu A^*; Griesing S; Rybachuk M; Lu Q B; Duley W W

来源：Journal of Applied Physics, 2007, 102(7): 074311.

DOI：10.1063/1.2786708

The growth, surface morphology, and electronic binding states of diamondlike films deposited by femtosecond laser ablation on Si wafers at 77 K have been studied in order to elucidate the mechanical properties of this material. Nanoscale buckling has been observed and is found to have a morphology that exhibits a strong dependence on film thickness. Nanobuckling takes the form of quasiperiodic discrete pointlike excursions extending over widths of 50-100 nm. This morphology converts to a regular structure of grooves/ripples with a modulation period of 30-50 nm as the film thickness increases to 300-600 nm. We find that microhardness is not changed in regions where nanobuckling is present. Analysis of Raman and x-ray photoelectron spectra (XPS) demonstrate that nanobuckling can be attributed to the relaxation of internal stress and to the formation of strong C-Si covalent bonds at the C-Si interface. XPS spectra show that the C 1s peak is broadened compared to that found in spectra of films deposited using nanosecond laser ablation. This is found to be consistent with a composition that includes sp, sp(2), and sp(3)-bonded carbon. The unique composition of these films suggests that these materials may find application in electromechanical devices.

• 出版日期2007-10-1