Carrier diffusion-wave transport effects on the “dip” (notch) phenomenon in photocarrier radiometric frequency response

In this study, the anomalous “dip” phenomenon, which has been observed in the heterodyne mode of photocarrier radiometry and characterized by a sudden amplitude depression (notch) accompanied by a 180° phase shift, is investigated. A nonlinear photocarrier radiative theory is presented by integrating the trap-state diffusion-wave theory with the n–p product recombination model. Based on this theory, the physical mechanism behind the “dip” phenomenon was analyzed, and the relevant semiconductor parameters were determined using experimental photocarrier radiometry signals from a silicon wafer. The carrier kinetic signals were compared between diffusion-wave and non-diffusion-wave models, along with comparisons between single-trap and double-trap configurations. By integrating carrier-wave diffusion into the nonlinear double-trap kinetics and the n–p product recombination formalism, this work extends the existing theoretical framework for the “dip” phenomenon and provides a more complete physical description for the quantitative characterization of trap-state dynamics in p-type semiconductors with obvious potential extension to n-type semiconductors.