The influence of pressure of methane atmosphere on the pulsed laser deposited (PLD) amorphous carbon layers (a-C:H) were studied, on the structure on atomic scale as well as on the electronic levels near the band edges. Raman scattering, measured by two different probing wavelengths, show the absence of graphitic ordering of sp2 hybridized carbons. The samples prepared at low methane pressure are characterized with spectra, similar to the spectra of diamond-like carbon. Infrared absorption of PLD films is dominated in the C-H bond stretching region by the bands due to sp3 CH3 and sp3 CH2 vibrations, however, a weak, widely distributed band also appears over 3000 cm-1. Photoluminescence (PL) can be excited in these samples with decreasing wavelength below 400 nm (over 3.1 eV) and a steep increase of PL intensity occurs below 250 nm (over 4.9 eV). Some distinct PL bands can be distinguished in wavelength region of 270-450 nm (4.6-2.7 eV), the appearance and intensity of which shows correlation with the applied methane pressure.
- Pulsed laser deposited
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Mechanical Engineering
- Materials Chemistry
- Electrical and Electronic Engineering