THz plasmonics and electronics in germanene nanostrips

Abstract

Germanene nanostrips (GeNSs) have garnered significant attention in modern semiconductor technology due to their exceptional physical characteristics, positioning them as promising candidates for a wide range of applications. GeNSs exhibit a two-dimensional (buckled) honeycomb-like lattice, which is similar to germanene but with controllable bandgaps. The modeling of GeNSs is essential for developing appropriate synthesis methods as it enables understanding and controlling the growth process of these systems. Indeed, one can adjust the strip width, which in turn can tune the bandgap and plasmonic response of the material to meet specific device requirements. In this study, the objective is to investigate the electronic behavior and THz plasmon features of GeNSs (≥100 nm wide). A semi-analytical model based on the charge-carrier velocity of freestanding germanene is utilized for this purpose. The charge-carrier velocity of freestanding germanene is determined through the GW approximation ( m·s−1). Within the width range of 100 to 500 nm, GeNSs exhibit narrow bandgaps, typically measuring only a few meV. Specifically, upon analysis, it was found that the bandgaps of the investigated GeNSs ranged between 29 and 6 meV. As well, these nanostrips exhibit -like plasmon dispersions, with their connected plasmonic frequency (≤30 THz) capable of being manipulated by varying parameters such as strip width, excitation plasmon angle, and sample quality. These manipulations can lead to frequency variations, either increasing or decreasing, as well as shifts towards larger momentum values. The outcomes of our study serve as a foundational motivation for future experiments, and further confirmation is needed to validate the reported results.

Dataset for Electronics and Plasmonics in Graphene, Silicene, and Germanene Nanostrips

“…Despite this, we proceeded to explore the potential applications of wide GNRs in biosensing using this approach [29,30]. Recently, we have enhanced our calculations by employing the GW approximation method to investigate silicene and germanene strips [31,32]. Therefore, in this current study, our aim is not to reiterate the previously stated findings but rather to present a comparative analysis of the electronic properties and plasmon characteristics of GNRs, SiNRs, and GeNRs, all possessing a ribbon width of 155 nm.…”

“…However, it is worth noting that a comprehensive analysis of these parameters can be found in Refs. [31,32].…”

“…In Equation ( 8), e, ε, q, θ, and N 2D represent the electron charge, dielectric constant, wave vector, excitation angle, and 2D charge density, respectively. Specifically, the 2D charge density can be employed to customize Equation ( 8) and analyze the ribbons as either isolated systems or periodic arrays using the following expression [13,25,31,32]:…”

“…Here, N 1D is the one-dimensional (1D) charge density, and d is the vacuum distance between attached ribbons. Subsequently, Equation (8) can be formulated as follows [32]:…”

“…For further details, see Refs. [31,32]. The ground-state properties of 2D Dirac-like materials (i.e., graphene, silicene, and germanene) were determined through DFT using the Abinit software (Version 6.3) [34], with a specific focus on the LDA [35].…”