Raman and photoluminescence study of magnetron sputtered amorphous carbon films

• Published in: Thin solid films 2002-07, Vol.414 (1), p.18-24
• Main Authors: Papadimitriou, D., Roupakas, G., Xue, C., Topalidou, A., Panayiotatos, Y., Dimitriadis, C.A., Logothetidis, S.
• Format: Article
• Language: English
• Subjects: Amorphous materials; Carbon; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Elemental semiconductors; Elemental semiconductors and insulators; Exact sciences and technology; Infrared and raman spectra and scattering; Luminescence; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Raman scattering; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(02)00442-X

The structural and optical properties of amorphous carbon films, grown by r.f.-magnetron sputtering on silicon substrates, were studied by Raman and photoluminescence spectroscopy in dependence of the substrate bias voltage V b. The intensity ratio I(D)/ I(G) of the Raman bands of disordered graphite ( D-band) and graphite (G-band) decreased significantly (a) by reversing bias from positive (+10 V) to negative (−20 V) and (b) by reducing the negative bias from −200 to −120 V. The intensity ratio I(D)/ I(G) exhibited an almost flat minimum in the bias-region from −120 to −20 V which is indicative of an increase of the fraction of sp 3-bonded material. In the same bias-range, photoluminescence emission at 2.2–2.5 eV appeared blue-shifted and more efficient. Changes in photoluminescence energy are attributed to increase of sp 3 content of the films becoming more transparent when deposited at substrate-bias between −20 and −120 V. Increase of photoluminescence intensity is probably related to increased number of defects due to increasing structural disorder.