Abstract

In this paper, we present a simple way to increase the sensitivity of polarization modulation infrared reflection–absorption spectroscopy (PM-IRRAS) for the study of ultrathin films deposited on dielectric and semiconductor substrates. The enhancement of the absorption band intensity is obtained by reducing the signal arising from the substrate. This is achieved by adding a polarizer after the sample in order to balance the polarized reflectivities of the sample. As a consequence, the contribution of the film to the PM-IRRAS signal is increased relative to that of the substrate. An enhancement factor of about 10 has been obtained for ultrathin organic films deposited on glass and spread at the air–water interface. This method has also allowed the study of the very thin native oxide layer present on silicon without the need for the reference spectrum of bare silicon.

Dual-channel dynamic modulation for polarization-dependent absorption by gating ultrathin TiN films in the near-infrared region

Yetian Wang, Huan Jiang, Huafeng Dong, and Weiren Zhao
Opt. Mater. Express 13(11) 3242-3251 (2023)

Effect of film absorption on a film-substrate reflection polarizer

M. Ruiz-Urbieta and E. M. Sparrow
J. Opt. Soc. Am. 63(2) 194-200 (1973)

Specific approach of generalized ellipsometry for the determination of weak in-plane anisotropy: application to Langmuir–Blodgett ultrathin films

B. Lecourt, D. Blaudez, and J.-M. Turlet
J. Opt. Soc. Am. A 15(10) 2769-2782 (1998)

Reflection of light in a long-wavelength approximation from an N-layer system of inhomogeneous dielectric films and optical diagnostics of ultrathin layers. I. Absorbing substrate

Peep Adamson
J. Opt. Soc. Am. B 20(4) 752-759 (2003)

Reflection of light in a long-wavelength approximation from an N-layer system of inhomogeneous dielectric films and optical diagnostics of ultrathin layers. II. Transparent substrate

Peep Adamson
J. Opt. Soc. Am. B 21(3) 645-654 (2004)