The effect of annealing in an ultrahigh vacuum on the chemical structure of diamondlike carbon (DLC) was investigated using photoelectron spectroscopy, thermal desorption spectroscopy, electrical resistivity, and micro-Raman spectroscopy measurements. The line shapes of the C 1s photoelectron spectra depended on annealing temperature. The relative intensities of four chemical components in the spectra were quantitatively evaluated: s p3 carbon with carbon-carbon bonds (C-C s p3 carbon), s p2 carbon with carbon-carbon bonds (C-C s p2 carbon), s p2 carbon with hydrogen-carbon bonds (H-C s p2 carbon), and s p3 carbon with hydrogen-carbon bonds (H-C s p3 carbon). The variation of the ratio of the components demonstrated that hydrogen in DLC is emitted to the outside in between 450 and 600 °C, and the remaining DLC is graphized above 600 °C. The increase in the asymmetry of the C 1s spectra and the decrease in the electrical resistivity of the DLC film with annealing temperature agree with the picture that the H-C bonds in DLC produces large free spaces in the structure, which inhibit conductive routes and lead to high electrical resistivity.
ASJC Scopus subject areas
- Physics and Astronomy(all)