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Immunoassay in biomedical field has attracted more and more attention, and surface plasmon technology is an effective detection method. Electroluminescent devices are suitable for excitation light source of surface plasma technology because of its low energy consumption and small size. In this paper, a light-emitting chip based on MIS structure is designed, and its electroluminescence principle and its internal electron tunneling principle are studied. Simultaneously, the structure and production process of the chip are proposed. The plasma oscillation frequency of doped silicon and the asymptotic frequency corresponding to the SPP dispersion curve of each interface in each MIS junction are calculated and analyzed, and the relationship between the asymptotic frequency and the wavelength of the light emission spectrum of the device is deduced. Finally, the luminescence spectrum wavelength corresponding to the asymptotic frequency of each interface is obtained, which lays a theoretical foundation for future experiments to verify whether the asymptotic frequency of each interface of the MIS junction is consistent with the peak value of the device luminescence spectrum.

In recent years, the plasma gap resonance maintained by metal-film-coupled nanostructures has attracted extensive attention. This mainly originates from its flexible control of the spectral response and significantly enhanced field strength at the nanoparticle–film junction. In the present study, the tunability of local surface plasmon resonances (LSPRs) of nanorods coupled to a gold film is studied theoretically. To this end, the plasmonic resonances in the nanostructure of individual silver nanorod–gold film (AgNR-film) with different parameters are investigated. Obtained results show that the refractive index sensitivity (S) of nanostructures to the environment increases as the aspect ratio (Ar) of nanostructures increase. It is found that when the aspect ratio (Ar) is set to 3.5, the figure of merit (FOM) is the highest. Moreover, the variation in the gap distances of the nanorod monomer–gold film, electric field distribution of nanorods dimer, and the corresponding impact on the gold film are studied. It is concluded that the gap size of nanostructures has an exponential correlation with the resonance wavelength. Considering the remarkable influence of the gap size and the surrounding medium environment on the spectral shift of AgNR-film nanostructures, potential applications of the structure as a refractive index sensor and biomolecule measurement are proposed.

In this paper, the finite element method is used to calculate the extinction optical properties and electric field distribution of gold core silver shell nanorod-gold film nanostructures. The volume ratio of silver and the length diameter ratio of core-shell nanorods can be changed by controlling the thickness of silver layer, which can realize the regulation of the longitudinal mode peak position from 600 to 900 nm. The electric field intensity of the core-shell nanorod-gold film structure increases with the increase of the volume ratio of silver. Silver is the plasmon material with the smallest loss in the visible light region, due to its small imaginary part of the dielectric function and lower plasma damping than gold. Therefore, with the increase of the volume ratio of silver, the extinction spectrum intensity of the gold core silver shell nanorod-gold film increases obviously, and the blue shift of the peak position and the narrowing of the full width at half maximum of the wave shape are obvious changes. At the same time, the structure gap confines the light to the deep sub wavelength range, which will produce a hot spot in the gap, which will enhance the electric field.

In this paper, a kind of light-emitting tunnel junction composed of three layers of metal–insulator-semiconductor (MIS, Au-Al2O3-Si) is introduced and this structure mainly relies on electron tunneling to excite SPPs. The finite element method is used to calculate the electric field distribution and extinction spectrum of the silver nanorod (AgNR) placed on the metal–insulator-semiconductor tunnel junction (MIS-AgNR). In the simulation, the influence of tunneling current on the strength of SPPs propagating along the metal surface is quantitatively studied by changing the thickness of the insulator layer of the MIS tunnel junction and the bias voltage across it. The AgNR is placed on the tunnel junction, and the gap distance between the gold surface of the MIS structure and the AgNR is changed to qualitatively study the relationship between the extinction characteristics of the AgNR and the gap distance. The study found that the amount of the tunneling current is proportional to the intensity of the SPPs on the metal surface. In the range of 4 nm–20 nm gap distance, the adjustment of the resonance peak position in the 500 nm–700 nm range of the extinction spectrum is realized. As the gap distance increases, the position of the resonant peak in the AgNR extinction spectrum will undergo blue-shift, and at the same time the intensity of the extinction peak will decrease. It is worth noting that the change of the blue-shift displacement is exponentially related to the change of the gap distance.