Plasmon Enhanced Electron Drag and Terahertz Photoconductance in a Grating-Gated Field-Effect Transistor with Two-Dimensional Electron Channel

Abstract

Public Reporting Burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. PLASMON ENHANCED ELECTRON DRAG AND TERAHERTZ PHOTOCONDUCTANCE IN A GRATING-GATED FIELD-EFFECT TRANSISTOR WITH TWO-DIMENSIONAL ELECTRON CHANNELReport Title ABSTRACTThe specific goal for the 1st year was to develop a physical model of the interaction between THz EM radiation and 2D electron channel of the grating-gated field-effect transistor. This physical model has been developed. The model predicts and allows to calculate photo induced dc correction to the sourse-drain voltage measured in experiment. Calculations demonstrate that dc photovoltage has resonant peaks at plasmon frequencies. Dependence of the peak positions, shape, and amplitude on the frequency, gate voltage, temperature, and FET geometry has been found. Distributions of the non-equilibrium electron density, electric fields, and currents in the 2D channel at resonance have been calculated. The results are in very good qualitative agreement with experiment. Plans for the coming year include numerical simulation of the dc photoresponce for various system designs in order to optimize device parameters and assess its potential as a THz detector.

Theory of Detection of Terahertz Radiation in Hybrid Plasmonic Structures with Drifting Electron Gas

“…where the factor Γ = 2 2 0 /( * √ ) has a meaning of the radiative decay rate. It should be noted that formula (27) contains the factor /( + Γ), which was omitted in the previous theory [15]. The emergence of this factor is stipulated by the sequential consideration of Maxwell's equations in the second order of perturbation theory.…”

“…Using Eqs. (15) and 16, we obtain the final formula, which expresses the photocurrent through the spatial Fourier harmonics of the electric field in the plane of 2DEG:…”

“…In the majority of previous theories devoted to the electro-optical characterization of plasmon structures [11,15], the momentum relaxation rate, , was assumed to be a constant quantity and independent of the magnitude of an applied field. However, in the case of A B semiconductor compounds, the electron scattering can be strongly intensified with increasing 0 due to the activation of the nonelas- tic electron-optical phonon interaction.…”

“…The physical asymmetry and/or strong nonlinearity of electrical characteristics of such devices are required for the detection of the external radiation. The asymmetry can be structural and builtin on the device fabrication stage (asymmetry of the contact system, modulation of the electron density [13,14]) or induced by an external electric field [15]. For example, the electrical asymmetry of contacts in the nanoscale Field-Effect Transistors (FET) [13,16,17] or the size-effect of carrier depletion in self-switching diodes (SSD) [18,19] is used for a detection of THz signals.…”

“…The modern theories of detection of THz radiation in hybrid plasmonic structures with 2DEG consider two main mechanisms: appearance of the photoresponse induced by the electron drift of 2DEG under the applied voltage [15] and the emergence of a photoresponse due to the spatial modulation of electron concentrations in structures with the asymmetric grating-gates [14,37,38]. These theories are based on the perturbative solutions of the nonlinear system of equations that includes the hydrodynamic and Maxwell's equations.…”