Grazing Angle Metal-Overlayer Infrared ATR Spectroscopy

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Abstract
The most sensitive reflection spectroscopic technique has been developed for studying the structure of thin films between a semiconductor and a metallic film. In this study, a metal-overlayer ATR technique was applied to measure the infrared spectra of interfacial layers. According to optical theory, this technique requires a high angle of incidence near the grazing angle in order to obtain optimum sensitivity. On the basis of the theoretical prediction, an optimized prism was designed. Our prism/thin film/ metal configuration yields an S/N ratio 5 times better than that achieved by the conventional reflection-absorption spectroscopy. This enhancement is not due to the so-called metal island effect, but is due instead to the high refractive index of the semiconductor prism.