Spectral Dependence of the Effective Photoconductivity of Crystalline Silicon Containing Amorphous Inclusions of Different Morphologies

This study investigates the effective photoconductivity of a crystalline silicon structure containing both spherical and cylindrical amorphous inclusions. A combined numerical and analytical framework was developed in which the wavelength-dependent concentrations of photogenerated carriers in the constituent phases were obtained by solving the steady-state carrier continuity equations, accounting for optical generation, diffusion, bulk recombination, and interfacial carrier losses. The phase-specific photoconductivities were homogenized using the self-consistent Bruggeman effective medium approximation, incorporating the phase volume fractions, depolarization factors, and inclusion geometry. Calculations were performed over the wavelength range of 500-1100 nm for structural disorder parameters γ = 0.05, 0.10, and 0.15 eV and total amorphous-phase volume fractions of 5-15 %. The calculated photoconductivity of monocrystalline silicon was found to reach approximately 0.105 S·m – 1 near 880-900 nm. The corresponding maxima for the heterogeneous structures are approximately 0.097, 0.089, and 0.080 S·m – 1, representing reductions of 7.6 %, 15.2 %, and 23.8 %, respectively. The crystalline matrix governs the overall spectral profile, whereas structural disorder broadens the long-wavelength response of the amorphous phase. Inclusion geometry appreciably affects the local photoconductivity; however, its effect on the normalized effective photoconductivity remains below approximately 0.04% for the configurations considered. The results demonstrate the applicability of the self-consistent Bruggeman effective medium approximation to multiphase photoconductive semiconductor structures containing inclusions of different geometries.