Observation of surface plasmon polaritons in 2D electron gas of surface electron accumulation in InN nanostructures

Abstract

Recently, heavily doped semiconductors have been emerging as an alternative to low-loss plasmonic materials. InN, belonging to the group III nitrides, possesses the unique property of surface electron accumulation (SEA), which provides a 2D electron gas (2DEG) system. In this report, we demonstrated the surface plasmon properties of InN nanoparticles originating from SEA using the real-space mapping of the surface plasmon fields for the first time. The SEA is confirmed by Raman studies, which are further corroborated by photoluminescence and photoemission spectroscopic studies. The frequency of 2DEG corresponding to SEA is found to be in the THz region. The periodic fringes are observed in the near-field scanning optical microscopic images of InN nanostructures. The observed fringes are attributed to the interference of propagated and back-reflected surface plasmon polaritons (SPPs). The observation of SPPs is solely attributed to the 2DEG corresponding to the SEA of InN. In addition, a resonance kind of behavior with the enhancement of the near-field intensity is observed in the near-field images of InN nanostructures. Observation of SPPs indicates that InN with SEA can be a promising THz plasmonic material for light confinement.

Hybrid Plasmonics and Two-Dimensional Materials: Theory and Applications

“…76 In the terahertz range, surface plasmon resonances were shown in a 2D gas within a thin InN¯lm manifested through surface electron accumulation e±ciently acting as a 2D material. 77…”

Electron Accumulation Tuning by Surface-to-Volume Scaling of Nanostructured InN Grown on GaN(001) for Narrow-Bandgap Optoelectronics

“…In particular, indium nitride (InN) offers remarkable features that are especially desirable for use in high-performance optoelectronic devices, such as a low electron mass (0.07 m 0 ); a narrow direct bandgap (0.6 – 0.7 eV); a high electron mobility (4850 cm 2 /Vs); and a widely tunable low-loss plasmon frequency in a large range of electron concentrations (10 17 – 10 21 cm –3 ), covering a broad region of the mid-infrared spectral range . As a consequence, several InN-based materials are especially attractive for use in high-electron-mobility transistors; two-dimensional electron gas systems; transducers in biocompatible chemical-sensing devices; infrared plasmonic devices; and most recently as tribo-piezoelectric nanogenerators . Additionally, recent attention has been given to the exploration of nonlinear optical properties of narrow-bandgap 2D materials designed for infrared plasmonics. , In particular, InN thin films have been highly investigated to be used as saturable absorber mirrors in ultrafast mode-locked fiber lasers for operation in the infrared spectral range around the 1.5 μm telecommunications band. , The femtosecond nonlinear response of InN displays a stable and ultrashort output emission, which allows a steady repetition rate of high-power pulses, without requiring any additional amplification. , The fabrication of InN-based devices is still challenging even after difficult growth conditions have been surmounted, such as the low dissociation temperature of InN ( T ∼ 500 °C) and the resulting high equilibrium vapor pressure of nitrogen over InN .…”

A terahertz near-field nanoscopy revealing edge fringes with a fast and highly sensitive quantum-well photodetector

“…However, due to the diffraction limit, the spatial resolution of conventional THz imaging systems is restricted to the sub-millimeter scale, which is not capable of nano-optical imaging of the fine structures. In recent years, the scattering-type scanning near-field optical microscopy (s-SNOM) ( Jiang et al, 2018b ; Seebacher et al., 2001 ; Chen et al., 2019 ) has become an effective tool in the nanoscale research of the semiconductor ( Schmidt et al., 2018 ; Madapu et al., 2018 ; Fei et al., 2012 ), plasmonic ( Wagner et al., 2014 ; Lang et al., 2018 ), biology ( Jiang et al., 2018a ), and dielectric systems ( Atkin et al., 2012 ). Usually, a sharp scanning probe of atomic force microscopy (AFM) ( Klarskov et al., 2017 ) is placed in the vicinity of the sample surface to acquire high spatial frequency (momentum) properties.…”