1656
J . Phys. Chem. 1993, 97, 1656-1660
Determination of the Optical Properties of Si/SiO* Surfaces by Means of Ellipsometry, Using Different Ambient Media Mikael Landgren’ and Bengt Jiiasson Division of Physical Chemistry 1, Chemical Center, Uniuersityof Lund, P . 0 . Box 124, S-22100 Lund, Sweden Received: August 24, 1992; In Final Form: December I , 1992
The optical properties of a silicon surface covered with an oxide layer about 30 nm thick have been determined by null ellipsometry. The complex refractive index of the silicon and the refractive index of the transparent oxide layer and its thickness have been determined simultaneously by measurements in different surrounding media. Using different surrounding media proves to give higher accuracy than the alternative of using different angles of incidence. The determination was made a t three different wavelengths: 401.5,448.8, and 600.4 nm. The influence of errors in the apparatus and in the optical model used has also been estimated.
Introduction Ellipsometry is one among many optical techniques which are available today for the study of optical properties of thin films. It relics on the fact that the state of polarization of a light wave is altered upon reflection at an interface. This change is extremely sensitiveto surface properties, and it can, furthermore, be detected with high accuracy. Thus, ellipsometry can be used to study growth or adsorption of very thin films (
