Spatial dispersion of the high-frequency conductivity of two-dimensional electron gas subjected to a high electric field: Collisionless case

Abstract

We present the analysis of high-frequency (dynamic) conductivity with the spatial dispersion, σ(ω, q), of two-dimensional electron gas subjected to a high electric field. We found that at finite wavevector, q, and at high fields, the high-frequency conductivity shows following peculiarities: strong non-reciprocal dispersion; oscillatory behavior; a set of frequency regions with negative σ ′ ; non-exponential decay of σ ′ and σ ′′ with frequency (opposite to the Landau damping mechanism). We illustrate the general results by calculations of spectral characteristics of particular plasmonic heterostructures on the basis of III-V semiconductor compounds. We conclude that the detailed analysis of the spatial dispersion of the dynamic conductivity of 2DEG subjected to high electric fields is critically important for different THz applications.

Modified rigorous coupled-wave analysis for grating-based plasmonic structures with delta-thin conductive channel. Far- and near-field study

“…where J 2D x,j is the Fourier-vector formed by J 2D ω,m,x components. The first equation in (8) expresses the continuity of the tangential component of electric field and second equation describes the discontinuity of magnetic field component due to the presence of the conductive 2D layer [33,34]. In the frames of the linear response theory, J 2D ω,m,x = σ 2D ω,m E ω,m,x , where high-frequency sheet conductivity, σ 2D ω,m , takes into account both frequency and spatial dispersion of the 2DEG.…”

“…Particular examples of σ 2D ω,m for the 2DEG with parabolic spectrum can be found in Refs. [8], [19]. For the electrons with Dirac spectrum, as in the graphene, σ 2D ω,m can be obtained using Kubo formalism (see Refs.…”

“…The cold zone of H y component occupies middle region of the bar near the bottom face. In the plane of 2DEG, |H y (x, z)| is a discontinuous quantity according boundary conditions (8).…”

“…Recently, great attention has been paid to exploitation of the subwavelength metasurfaced structures in THz and Far-infrared spectral ranges. Particularly, the semiconductor structures with surface-relief gratings [5,6], quantum well (QW) heterostructures [7,8] or graphenebased structures [9] incorporated with metallic gratings are widely discussed as potential efficient emitters and detectors of the THz radiation [10]. In such structures, the gratings play a role of the coupler, facilitating the resonant interaction between incident electromagnetic (em) waves and charge density waves such as surface plasmonpolaritons or 2D plasmons.…”

“…Latter can be solved, for example, using Galerkin schemes with guaranteed convergence. The IE technique has been exploited for the different problems including investigations of 2D plasmon instabilities under the grating [8,19,20], detection of THz radiation [21][22][23] and interaction of THz radiation with conductive-strip gratings [24,25]. In spite of apparent advantages with respect to fast convergence, this method is typically formulated for modeling structures with simple geometries and grating is treated as delta-thin.…”