External excitation of hybrid plasma resonances in a gated semiconductor slab: An analytical study

Abstract

We derive at first-order the carrier and velocity conservation equations and a pseudo-2D (P2D) Poisson equation in order to obtain an analytical model suitable for the study of the optical and electrical excitations of the plasma modes in a gated semiconductor channel of arbitrary thickness. We calculate the dispersion relation of the plasma waves appearing in the channel and the frequencies of the eigen modes for different boundary conditions (BCs). Then, we obtain and comment different THz-range frequency responses to an uniform optical beating or to an electrical excitation applied on the gate or the drain contacts. The effects of the different stimulations and boundary conditions are compared, and the responses, characterized by sharp resonances in the THz range, are interpreted as the sum of the contribution of the different hybrid plasma modes excited in the slab.

Terahertz Small-Signal Response of Field-Effect Transistor Channels

“…The description of the transistor is obtained by a one-dimensional (1-D) analytical hydrodynamic model coupling charge and drift velocity conservation equations with a pseudo-two-dimensional (P2D) Poisson equation [9], [15], [16]. In this framework, the amplitude of the potential oscillation verifies (1) where stands for the 3-D electron density in the channel, is a parameter describing the transverse geometry of the device [17] where is the dielectric constants in the channel and in the dielectric between the channel and the gate, respectively.…”

Hybrid plasma modes in transistors: linear and non-linear responses

“…In both cases, the resonances frequencies f p cannot overreach the 3D plasma frequency [see Ref. [8] for further details]. …”

“…d is related to the gate-to channel capacitance C gc = ε s L/d with L the gate length and ε s the permittivity of the insulator. ε c is the dielectric constant, ν the velocity relaxation rate and m the electron effective mass which will be taken equal to their typic values in InGaAs at room-temperature [8]. V g and V th are the gate and threshold voltages, respectively.…”

“…This model allows to study the different kinds of external excitations of plasma modes (THz, optical or both) and different geometries. In particular, we demonstrate the dispersivity of the plasma in the FET channel, the electron gas shifting progressively from a 2D plasma dynamic behavior at low frequency to a 3D plasma at high-frequency, that is why we introduced the concept of hybrid plasma modes [8].…”

“…We recently proposed an original analytical model based on hydrodynamic equations and a pseudo-2D (P2D) Poisson equation to overtake these limitations [8]. This model allows to study the different kinds of external excitations of plasma modes (THz, optical or both) and different geometries.…”