Analytical integration of small-signal transport equations in an MIS structure at flat-band condition

The small-signal transport equations are solved analytically in a homogeneously doped MIS structure at flat-band condition. We can establish exact expressions of ac carrier density, electric field, and potential distributions in the MIS structure for any frequency. The plot of these expressions, in the frequency range from 10^-3to 10⁹Hz, proves the existence of majority and minority modes. A complete impedance expression is sufficient to determine all equivalent circuit components of the MIS structure at flat-band condition. The proposed method is valid for any bulk lifetime of carriers and for any semiconductor thickness.