Nonlinear high-frequency conductivity in semiconductors

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Abstract
We study the nonlinear effects of the electron conductivity in semiconductors when a strong high frequency (HF) electric field is applied together with a direct current (dc) electric field. The dynamic equation that we used is different from the Boltzmann equation by considering the memory effect for drift oscillating motion of electrons. Using the drifted temperature model, we derive a set of equations from which the amplitude and phase of each harmonic component of the electron drift velocity and the electron temperature can be obtained. In the weak-HF-field limit our approach reduces to the well-known memory-function method. We have calculated the conductivity of electrons in a bulk n-type GaAs sample. The nonlinear effects are shown. In particular, the dc conductivity decreases and definitely becomes negative with increase of the first- and second-harmonic components of the applied HF field. Comparison is made with experiments.