Acoustically-driven surface and hyperbolic plasmon-phonon polaritons in graphene/h-BN heterostructures on piezoelectric substrates

Abstract

Surface plasmon polaritons in graphene couple strongly to surface phonons in polar substrates leading to hybridized surface plasmon-phonon polaritons (SPPPs). We demonstrate that a surface acoustic wave (SAW) can be used to launch propagating SPPPs in graphene/h-BN heterostructures on a piezoelectric substrate like AlN, where the SAW-induced surface modulation acts as a dynamic diffraction grating. The efficiency of the light coupling is greatly enhanced by the introduction of the h-BN film as compared to the bare graphene/AlN system. The h-BN interlayer not only significantly changes the dispersion of the SPPPs but also enhances their lifetime. The strengthening of the SPPPs is shown to be related to both the higher carrier mobility induced in graphene and the coupling with h-BN and AlN surface phonons. In addition to surface phonons, hyperbolic phonons appear in the case of multilayer h-BN films leading to hybridized hyperbolic plasmon-phonon polaritons (HPPPs) that are also mediated by the SAW. These results pave the way for engineering SAW-based graphene/h-BN plasmonic devices and metamaterials covering the mid-IR to THz range.

Effect of quasiparticle excitations and exchange-correlation in Coulomb drag in graphene

“…A transport-dominated regime, with τ >> τ ee , is assumed, where τ and τ ee are, respectively, the carrier transport and the electron-electron interaction times. h-BN is an anisotropic wide bandgap insulator whose in-and out-of-plane frequencydependent relative permittivities, ϵ x ðωÞ and ϵ z ðωÞ respectively, have opposite sign in the two reststrahlen bands, thus supporting a series of hyperbolic phonon modes that are confined within these bands (see Supplementary Note 1 for mathematical expressions and graphs of ϵ xðzÞ ðωÞ) 36,41 . To model the h-BN layer, we first define the expressions ϵ s ðωÞ ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi ϵ z ðωÞϵ x ðωÞ p and ϵ a ðωÞ ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ϵ z ðωÞ=ϵ x ðωÞ p , that are plotted in Fig.…”

Modulation of terahertz radiation from graphene surface plasmon polaritons via surface acoustic wave

“…The en waves when t Fig [19,20], quan des [24][25][26][27] Ps on the is leads to dielectric ouin zone he folded on formed alize band must be frequency es another e and the has been he surface t separate s of these ce of the AW-based of charge including tion metal utions, the 0s [28]. In these studies, the SAW fields were used to generate "dynamic" grating on the metal surfaces [29][30][31] or graphene layers [32][33][34] to interact with surface plasmon or light.…”

Quasiparticles in graphene and other 2D materials: modulation by a Surface acoustic wave and contribution to Coulomb drag

“…In figure 2.8 (a), measured FTIR transmittance spectra of G/AlN/Si are shown and compared with bare AlN/Si and Si substrates. The decrease in the transmittance between 0.08 eV and 0.12 eV is due to the reststrahlen band of the AlN (ω TO AlN = 0.083 eV, ω LO AlN = 0.11 eV [115]), while the overall transmittance is decreased to approximately 50% by the free carrier absorption in Si. Figure 2.8 (b) shows the FTIR reflectance spectra of h-BN/AlN/Si and AlN/Si.…”