Admittance spectra of silicon photocells: From dark mode to weak illuminate mode

Abstract

The results of an experimental analysis of the admittance spectra structure in the frequency range of a harmonic test signal from 1 kHz to 10 MHz are presented. The signal amplitude did not exceed 20 mV, the surface density of the recorded photocurrent was limited to a value of 20 mA/cm2. Variants of PVC (Photovoltaic Cells) structural schemes in the dynamic approximation, optimal combinations of localized L, R, C parameters explaining the recorded spectra, dispersion characteristics, and Nyquist diagrams are discussed. A significant contribution of the inductive component in the PVC structural scheme is observed in both dark and weakly illuminated modes. The inductive component is associated with the current flow geometry, primarily with lateral currents. The screening effect in the p-n junction zone was noted at low illumination of the PVC surface; it manifests itself in the loss of the dependence of the admittance spectra on the bias voltage.