An automatic system for broadband complex-admittance measurements on MOS structures

The design of an automatic apparatus for broadband complex admittance measurements on MOS structures is considered in detail. An apparatus is described which operates in a frequency swept mode over the range 10 Hz-100 kHz. It can measure admittances having very small loss angles with a total uncertainty in Gm/ omega Cm of the order 10-4 over the full frequency range. On typical MOS devices this allows the accurate determination of interface-state parameters at densities as low as 2*109 states cm-2 eV-1.