Scanning angle differential reflectometry around the Brewster angle to probe ultrathin dielectric films

An analysis is made of a differential reflection method for optical probing of ultrathin dielectric films on transparent substrates by depositing a second ultrathin dielectric layer with arbitrary parameters to the film under study and measuring, in the vicinity of the Brewster angle, the angular spectrum of the change in the reflectance of p-polarized light induced by the deposited layer. It is shown that in the long-wavelength approximation the half-width of this spectrum depends linearly on the thickness of the initial ultrathin film and is independent of the parameters of the second layer. A novel technique, which permits simultaneous determining the dielectric constant and thickness of homogeneous ultrathin dielectric films by differential reflectance measurements, is developed.