Study On The Luminescence Characteristics Of GaN LED Enhanced By Local Surface Plasmons

Light Emitting Diode(LED),as a new generation of lighting source,is favored by people because of its low power consumption,high brightness,and no pollution,etc.Currently,the introduction of metal nanoarray structure on the surface of LED chip to excite localized surface plasmon(LSP)to enhance the optical performance of LED is one of the hot research topics.Based on LSP resonance technology,this paper investigates the light-emitting characteristics of Ga N-LED with high output power based on LSP enhancement from two directions,namely,the enhancement of internal spontaneous radiation and the improvement of light extraction efficiency by external light output power.The optical properties of Ga N-LEDs are also analyzed in depth.The main contents of this paper are as follows:(1)This paper firstly designs a Ga N-LED chip structure with an array of silver(Ag)nanodiscs embedded in a p-layer,and analyzes the electric field far-field radiation from the surface of Ag nanoparticles as well as the electric field near-field intensity in two directions to realize the LSP of Ag nanoparticles to excite its surface electric field localization enhancement.The mechanism of LSP coupling with the active layer of LED to enhance its spontaneous radiation rate is revealed.By parameterizing the period(a)and height(h)of the scanning disc at a fixed radius,the spontaneous radiation rate after LSP coupling is calculated to be increased by 4.79 times compared with the initial structure,and the internal radiation source power integral is increased from 0.037 to0.177 under the optimal structure,and the dipole excitation is also obtained.The relationship of its energy distribution after coupling changes with the size of Ag nanodisc,and this result can be used for the modulation of nanoparticle resonant frequency and optical bandwidth.(2)The enhanced energy after coupling inside the LED active layer is not radiated outward,and its energy is confined to the surface of the Ag nanodisc.On this basis,a two-dimensional photonic crystal triangular array structure is proposed in this paper to increase the surface light output power and thus improve the light extraction efficiency.The highest value of transmittance reached under the optimal structure is 0.32.While changing the size of the Ag nanodisc,the transmittance is almost constant and the optical output power appears to be locally enhanced,with the top surface power integral increasing from 0.021 to 0.131,indicating that the top energy shows a local enhancement.In the optimal structure,the light output power is enhanced by a factor of 5.47,while changing the disc size enhances the light extraction efficiency by a factor of 1.79 in the optimal structure.The energy change caused by the enhanced spontaneous radiation rate in the above findings can be used to modulate the resonant frequency of metal nanoparticles and also to achieve modulated optical bandwidth.The enhancement of the external light extraction efficiency can provide a reference for enhancing the brightness of LED lighting and the field of light display.