DETERMINATION OF INTERFACE TRAP DENSITY IN UNIPOLAR STRUCTURES USING QUASISTATIC C-V METHOD

Pavol Písečný - Milan Ťapajna - Ladislav Harmatha - Andrej Vrbický

   The design and realization of computer controlled measurement for determination of the trap density on the insulator-semiconductor interface (D_it) using quasistatic C-V method is described. This method is simple, nevertheless, it is the most accurate technique for D_it determination in comparison to other ones. Using appropriate theoretical analysis, one can also obtain the energy distribution of interface trap density in the bandgap. In the experiment, two series of samples were used: (1) high-quality MOS structures prepared by different oxidation processes and (2) samples irradiated by 305MeV Kr⁺ and 710MeV Bi⁺ ions with different fluencies. From pulsed MOS capacitor measurement (the so-called C-t technique), surface generation velocity S_g was evaluated and, subsequently, the interface capture cross-section was calculated. All the results are discussed with regard to the amount of interface defects as well as their electrical activity.

Keywords: MIS structure, quasistatic C-V measurement, interface trap density

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