## Abstract

Diagram methods are applied for evaluating the ac effective conductivity σ^{*}(ω) of a disordered semiconductor (e.g., a highly doped compensated semiconductor, a composite, etc.). Expressions for σ^{*}(ω) are obtained in a number of approximations — the cumulant approximation, the self‐consistent moment approximation, and the effective medium approximation. For a random binary mixture which consists of two materials with conductivities σ_{1} and σ_{2}, the dependences of real and imaginary parts of σ^{*}(ω) on the frequency ω of the external electric field, volume fraction x of the most conducting material and the ratio of the conductivities σ_{2}/σ_{1} are presented for all approximations mentioned. For a metal‐insulator mixture (σ_{2} = 0) on the onset of percolation the cumulant and effective medium approximations predict the following behaviour of σ MI*(ω): σ MI*(0) ∼ (x — x_{c})^{t}, σ MI*(ω) ∼ ω^{s}, here t = 1, s = 1/2. The results, obtained for σ MI*(ω) are compared with those of computer simulation in the model of fully penetrating spheres (Balberg and Binenbaum). The cumulant approximation is in good agreement with the computer results.

Original language | English |
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Pages (from-to) | 491-503 |

Number of pages | 13 |

Journal | physica status solidi (b) |

Volume | 169 |

Issue number | 2 |

DOIs | |

State | Published - 1 Jan 1992 |

Externally published | Yes |

## ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics