Graphene Plasmonics in Sensor Applications: A Review

Abstract

Surface plasmon polaritons (SPPs) can be generated in graphene at frequencies in the mid-infrared to terahertz range, which is not possible using conventional plasmonic materials such as noble metals. Moreover, the lifetime and confinement volume of such SPPs are much longer and smaller, respectively, than those in metals. For these reasons, graphene plasmonics has potential applications in novel plasmonic sensors and various concepts have been proposed. This review paper examines the potential of such graphene plasmonics with regard to the development of novel high-performance sensors. The theoretical background is summarized and the intrinsic nature of graphene plasmons, interactions between graphene and SPPs induced by metallic nanostructures and the electrical control of SPPs by adjusting the Fermi level of graphene are discussed. Subsequently, the development of optical sensors, biological sensors and important components such as absorbers/emitters and reconfigurable optical mirrors for use in new sensor systems are reviewed. Finally, future challenges related to the fabrication of graphene-based devices as well as various advanced optical devices incorporating other two-dimensional materials are examined. This review is intended to assist researchers in both industry and academia in the design and development of novel sensors based on graphene plasmonics.

Keywords: 2D materials; biological sensors; graphene; photoelectric sensors; plasmonics.

Figure 1

(a) A schematic illustration of the atomic arrangement in graphene. (b) The honeycomb lattice (left) and the Brillouin zone (right) for graphene. a₁ and a₂ are the lattice unit vectors. b₁ and b₂ are the reciprocal lattice vectors. (c) The energy bands in the vicinity of the K and K’ points.

Figure 2

(a) The real and imaginary parts of the optical conductivity of graphene for various values of E_F. (b) The energy band structure of graphene, showing the Dirac point and Fermi level. (c) A comparison of the plasmon dispersion results for graphene and for various other materials. (a,b) are adapted from Reference [41]. © 2020 Society of Photo-Optical Instrument Engineers (SPIE).

Figure 3

Calculated optical conductivity values for graphene at a wavelength of 1.55 μm and a temperature of 300 K as functions of chemical potential. (a) The real and imaginary parts of the interband and intraband transition contributions. (b) The overall optical conductivity values. Both figures were adapted with permission from Reference [54]. © 2020 Optical Society of America.

Figure 4

(a) A scanning electron microscopy (SEM) image of a graphene nanoribbon (GNR) channel and electrode. (b) A schematic of the concept for a GNR-based plasmonic IR detector. (c) Dispersion relation for hybrid plasmon-phonon modes in graphene on SiO₂. (d) The polarization dependence of the normalized photocurrent. All figures are adapted from reference [72]. © 2020 American Chemical Society.

Figure 5

Graphene integrated metasurface photodetectors. (a) A schematic of a periodic micropatch array and (b) the performance data for field effect transistor (FET)-based mid-IR photodetectors with periodic micropatches. (c) A schematic illustration and (d) optical microscopy image of a graphene-based optical sensor made from gold heptamers sandwiched between two graphene monolayers. (a,b) are adapted from reference [85]. © 2020 American Chemical Society. (c,d) are adapted from Reference [86]. © 2020 American Chemical Society.

Figure 6

(a) A schematic showing the concept of a GNR–based biosensor and (b) an SEM image of a GNR array. Both figures are adapted from Reference [100]. © 2020 The American Association for the Advancement of Science.

Figure 7

Graphene integrated metamaterial absorbers. (a) A schematic of graphene embedded in an MIM absorber using hexagonal boron nitride (hBN) and (b) schematics of graphene coated over top of MIM absorbers together with absorbance data for graphene in the middle and the top of the insulator layers. (c) The absorbance plots of this device for various chemical potentials. (d) The absorbance of graphene coated over top of metal-insulator-metal (MIM) absorbers. (a) is reprinted from Reference [115] with the permission of AIP Publishing. (b–d) were adapted with permission from Reference [118]. © 2020 Optical Society of America.

Figure 8

(a) A schematic of a reflect-array of rod antennas integrated with graphene. (b) The calculated reflection spectra (upper panel) and phase of the reflected light (lower panel) for various graphene doping levels. Both figures are reprinted from Reference [123] with the permission of AIP Publishing.

Figure 9

(a) A schematic illustration of a phase modulator based on graphene embedded with metallic resonators. (b) An SEM image of the resonators. (c) The absorption spectra for various graphene Fermi levels. (d) A schematic illustration of a reconfigurable reflector based on graphene embedded in MIM-based metasurfaces. (a–c) are adapted from Reference [147]. © 2020 American Chemical Society. (d) is adapted from reference [148]. © 2020 American Chemical Society.