Electronic structure of pulsed laser deposited carbon thin films monitored by photoluminescence

• Published in: Diamond and related materials Vol. 12; no. 3; pp. 911 - 916
• Main Authors: Tóth, S., Caricato, A.P., Füle, M., Veres, M., Koós, M., Pócsik, I.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2003; Elsevier
• Subjects: a-C:H; Amorphous semiconductors, metallic glasses, glasses; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron states; Electronic structure of disordered solids; Exact sciences and technology; Infrared; Lattice dynamics; Photoluminescence; Physics; Pulsed laser deposited; Raman; Vibrational states in disordered systems; a-C:H; Raman; Infrared; Pulsed laser deposited; Photoluminescence; Raman spectra; Pulsed laser deposition; Amorphous state; Hybridization; Infrared spectra; Experimental study; Fabrication property relation; Carbon; Thin films; Electronic structure; Hydrogen bonds; Amorphous hydrogenated material; Vibrational modes
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(02)00354-0

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 sp 2 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 sp 3 CH 3 and sp 3 CH 2 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.