Abstract:
The peculiarities of the behavior of high-frequency conductivity of disordered semiconductors associated with the hopping transport of electrons in the impurity band with increasing temperature were studied. Via the pair approximation, it is shown that the transition (crossover) observed at low temperatures ($T\approx 1$ K) in the terahertz frequency range from an almost linear to a quadratic frequency dependence of the real part of conductivity can stay on with increasing temperature and be caused by the transition from relaxation conductivity with a variable-range (frequency-dependent) hopping distance to phononless conductivity with a fixed-range hopping distance.
Keywords:hopping conductivity, universality of the frequency dependence of conductivity, phononless conductivity.
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