Measuring on thin film electroluminescent devices

Nondestructive methods for the evaluation of film thicknesses in the stack of thin film electroluminescence devices are important tools in development, in degradation studies, and even in research concerning the basic processes in these devices. A simple model of the operation of these devices allows for a fitting procedure of the transferred charge/applied voltage characteristic, yielding the capacities of the semiconductor and dielectric films separately. Their thicknesses on the other hand can be assessed by Rutherford backscattering (RBS). With known values of the dielectric constants their comparison results in good agreement assuming a density of the vacuum-deposited films 5% less than the bulk values. (author)