Combined grazing-angle and normal-incidence reflectometry of absorbing media

We have studied the grazing-incidence differential-reflectance method for obtaining the dielectric function of absorbing media in terms of the derivatives R-p' and R-s' of the polarized light reflectances and found that it does not guarantee adequate accuracy for almost any values of the optical parameters. Therefore we modify that approach and describe what we believe is a novel method for the unambiguous determination of the optical constants n and k of a metal and other absorbing materials in terms of the ratio of the derivatives alpha = R-p'/R-s' at the grazing incidence and the normal incidence reflection coefficient R. Moreover, it is possible to express alpha through the logarithmic derivatives (1/R)R' in the vicinity of the grazing angle. The possibility of performing measurements at the unspecified angle without knowledge of the explicit value of this angle is an evident advantage of this technique. For the great majority of metals and semiconductors the relative errors in the optical constants are comparable to or less than the relative errors in the experimentally measured parameters. (C) 1999 Optical Society of America [S0740-3232(99)01302-2].16237137