An analysis method is developed to investigate the vibrational properties of thin films by use of infrared <i>in situ</i> ellipsometry. The procedure is based on the study of regions located in or outside the vibrational bands as a function of film thickness. Infrared index, line positions, bandwidths, and absorption intensities can be determined, even in the case of low oscillator strengths. As an illustration, C—H bonding of 100-nm-thick hydrogenated amorphous carbon films have been studied: Weak vibrations located at 1405 and 1440 cm<sup>−1</sup>, which had not been observed so far, are evidenced, thus revealing the presence of CH olefinic units and methyl groups bonded to sp<sup>2</sup>-configured carbon.
© 1999 Optical Society of America
(120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
(120.7280) Instrumentation, measurement, and metrology : Vibration analysis
(160.2750) Materials : Glass and other amorphous materials
(160.5470) Materials : Polymers
(300.6340) Spectroscopy : Spectroscopy, infrared
Thibaut Heitz, Bernard Drévillon, and Christian Godet, "Improvement of sensitivity in the analysis of vibrational properties of thin films by use of in situ ellipsometry:applications to hydrogenated amorphous carbon films," J. Opt. Soc. Am. B 16, 1044-1048 (1999)