Non-drude-like behavior of the photoinduced dielectric permittivity of GaAs and Si in the gigahertz range frequencies

Abstract

A non-drude-like behavior of the real part of the photoinduced permittivity ReåP of GaAs and Si samples in the gigahertz range was detected by direct resonator measurements under conditions of fiber-optic irradiation at a wavelength of ë = 0.97 microns with power changes P in the range of 0÷1 W. It is shown that, in accordance with the hypothesis of the exciton mechanism of the photoinduced microwave dielectric permittivity, ReåP increases with increasing P (approaching saturation above P = 200 mW) instead of decreasing within the framework of free charge carriers by Drude. The generality of the behavior of the real parts of the photoinduced permittivity observed in semiconductors of different types (straight-band GaAs and non-straight-band Si) in different electrodynamic systems (waveguides, resonators, metastructures) testifying to the universality of the exciton mechanism is demonstrated. Optically controlled metastructures in the GHz band containing resonant electrically conductive elements loaded with GaAs and Si samples are proposed for the first time: a metastructure based on linear dipoles and a half-wave electric dipole based on a multi-pass spiral. Gigahertz responses of metastructures and the transformation of responses associated with changes in the dielectric permittivity of Si and GaAs during photoexcitation were measured for the first time. Based on the hypothesis put forward about the effect of excitons on photoexcitation, the observed saturation effect of gigahertz photoinduced permittivity is discussed.