Engineering semiconductor hybrids for sensing

TL;DR

This paper investigates how a doped semiconducting substrate influences the plasmon spectrum in graphene-like 2D electron layers, revealing conditions for plasmon instabilities that can emit radiation, relevant for nano-plasmonic devices.

Contribution

It introduces a theoretical framework using the random-phase approximation to analyze plasmon behavior in hybrid 2D semiconductor structures with current-induced effects.

Findings

Identification of bifurcation of low-frequency plasmons under current flow

Discovery of surface plasmon instability leading to radiation emission

Dependence of critical wave vector on layer separation and distance from surface

Abstract

The effect of screening of the coulomb interaction between two layers of two-dimensional electrons, such as in graphene, by a highly doped semiconducting substrate is investigated. We employ the random-phase approximation to calculate the dispersion equation of this hybrid structure in order to determine the plasmon excitation spectrum. When an electric current is passed through a layer, the low-frequency plasmons in the layer may bifurcate into separate streams due to the current-driving effect. At a critical wave vector, determined by the separation between layers and their distance from the surface, their phase velocities may be in opposite directions and a surface plasmon instability leads to the emission of radiation. Applications to detectors and other electromagnetic devices exploiting nano-plasmonics are discussed.