Frequency dependence of the real part of the conductivity σ_1(ω) in the region of the transition from almost linear ( s < 1) to quadratic ( s ≈ 2) can indicate a change in the conduction mechanism (the transition from the variable-range to the fixed-range hopping with increasing frequency); in this case, the sharpness of the change in the slope of the frequency characteristic is related to the dependence of the preexponential factor of the resonance integral on the intercenter distance in the pair. The frequency dependence of the imaginary part of the conductivity σ_2(ω) has no kink in the vicinity of the transition frequency ωcr, remaining almost linear. A large dielectric loss angle |cotγ| = |σ_2|/σ_1 can indicate that the imaginary part of the conductivity at ω < ω_cr is defined by the larger zero-phonon contribution in σ_2^res the region of weak variation in the loss angle γ(ω), which significantly exceeds the relaxation contribution σ_2^res.
The effect of hybridization of electron states on the high-frequency conductivity of disordered semiconductors is studied. It is shown that the dependence of the pre-exponential factor of the resonance integral on the intercenter separation in a pair determines the abruptness of the change in conductivity mechanisms near the transition of the frequency dependence of the real part of the conductivity σ_1(ω) from sublinear to quadratic. The abruptness of the change of the conductivity regimes is associated with a rapid decrease in hopping distance with increasing frequency near the transition, which leads to a substantial relative decrease in the contribution from the phononless conductivity component in the variable-range hopping regime with increasing frequency and transition to the fixed-range hopping conductivity regime.
Рассмотрены особенности высокочастотной проводимости неупорядоченных полупроводников, связанные с прыжковым транспортом электронов по примесной зоне. В рамках парного приближения проведен расчет частотной зависимости вещественной части низкотемпературной бесфононной проводимости в области перехода (кроссовера) от линейной к квадратичной частотной зависимости проводимости. Показано, что кроссовер в терагерцовом диапазоне частот связан с переходом от режима проводимости с переменной длиной прыжка к режиму проводимости с постоянной длиной прыжка с ростом частоты. Ключевые слова: высокочастотная прыжковая проводимость, универсальность частотной зависимости проводимости, неупорядоченные полупроводники.
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