Determination of a mobile-ion concentration in the dielectric films of metal-insulator-semiconductor structures

An experimental technique for determining the surface concentration NS of mobile ions in dielectric films of metal-insulator semiconductor (MIS) structures is described. The technique is based on synchronous recording of the dynamic volt-ampere and low-frequency capacity-voltage characteristics of a sample under investigation. These experimental dependences are shown to ensure accurate extraction of the ion current peaks whose areas are proportional to Ns. These characteristics also allow the relaxation of the surface semiconductor potential to be found, which is needed for reconstructing the dependence of the convection ion current on the voltage drop across the insulation gap of the MIS capacitor. A comparative analysis with other known methods for determining NS is carried out. The proposed technique helps find a mobile-ion concentration from a similar to5 x 10(9) to 10(13)-cm(-2) range, including the case when ion current peaks do not appear on the current-voltage characteristics.