ON THE DETERMINATION OF CHARGE PROFILES IN EPITAXIAL LAYERS OF ZNSE BY CAPACITANCE MEASUREMENTS

The doping profile in semiconducting epitaxial layers is often deduced from the behavior of the capacitance of a Schottky contact evaporated onto the surface of the layer as a function of the bias voltage. It i s shown on the example of Au/ZnSe/GaAs heterostructures that the heter ojunction with the substrate in series with this Schottky contact lead s to erroneous profiles, if no special care is taken in the choice of the frequency used in measuring the capacitance. This frequency must b e chosen below the cutoff frequency which is apparent in the graphs of the capacitance vs the frequency.