OPTICAL-PARAMETER ANALYSIS OF THIN ABSORBING FILMS MEASURED BY THE PHOTOVOLTAGE METHOD

A special method for measuring the optical parameters of thin absorbin g films is presented. Within the method the radiation transmitted thro ugh the layer is measured. The transmitted radiation is detected by th e space charge region which is located in the substrate at the interfa ce with the layer. The space charge region acts as a photodetector pla ced just behind the layer. In this paper the method is applied to char acterize a system of an absorbing ZnSe film on a GaAs substrate. The v alues of the optical parameters of the film are evaluated. This means that the value of the thickness and the spectral dependences of both t he refractive index and extinction coefficient are determined. The spe ctral dependences of both optical constants are determined in the visi ble range. Finally, the comparison of our results obtained by this met hod with the results obtained from ellipsometric and reflectance measu rements is presented.