RUGOSITÉTHE PROBLEM OF SURFACE ROUGHNESS IN ELLIPSOMETRY AND REFLECTOMETRY

Une classification des surfaces rugueuses a été effectuée. Trois modèles d'un système substrat-film avec des interfaces rugueuses ont été définis. On présente aussi une approche théorique pour trouver une solution aux équations ellipsométrique et de réflectance (composants cohérents et incohérents généralement à incidence non normale pour ces derniers). Les principaux résultats sont donnés sous forme mathématique. Ces résultats sont utilisés dans une discussion et une interprétation des résultats expérimentaux.The classifications of rough surfaces has been performed. Three models of a system substrate-thin film with randomly rough boundaries have been defined. Also is presented the theoretical approach to the solution of the problem to find the ellipsometric parameters and reflectance (both coherent and incoherent components, generally at non-normal incidence) and the main results are given in mathematical form. These results are used in a discussion concerning their application at interpretation of experimental results

Optical Parameter Analysis of Thin Absorbing Films Measured by the Photovoltage Method

A special method for measuring the optical parameters of thin absorbing films is presented. Within the method the radiation transmitted through the layer is measured. The transmitted radiation is detected by the space charge region which is located in the substrate at the interface with the layer. The space charge region acts as a photodetector placed just behind the layer. In this paper the method is applied to characterize a system of an absorbing ZnSe film on a GaAs substrate. The values of the optical parameters of the film are evaluated. This means that the value of the thickness and the spectral dependences of both the refractive index and extinction coefficient are determined. The spectral dependences of both optical constants are determined in the visible range. Finally, the comparison of our results obtained by this method with the results obtained from ellipsometric and reflectance measurements is presented