Study on Modulation Bandwidth and Light Extraction Efficiency of Flip-Chip Light-Emitting Diode with Photonic Crystals

Abstract

In this study, the photonic crystal structure is employed to increase both the light extraction efficiency and the modulation bandwidth of flip-chip GaN-based light-emitting diodes (LEDs). The finite difference time domain method is utilized to investigate the influence of structure of photonic crystals on the Purcell factor and light extraction efficiency of flip-chip GaN-based LEDs. Simulation results show that the modulation bandwidth is estimated to be 202 MHz at current densities of 1000 A/cm2. The experimental result of modulation bandwidth is in accord with the simulation. The optical f-3dB of the device achieves 212 MHz at current densities of 1000 A/cm2 and up to 285 MHz at current densities of 2000 A/cm2. This design of photonic crystal flip-chip LED has the potential for applications in high-frequency visible light communication.

Enhancing light extraction efficiency of GaN LED by combining complex‐period photonic crystals with doping

“…In summary, our scheme proposed in this paper has the following advantages compared with other schemes: (1) The PhC array is added above the P layer to avoid affecting the electrical properties of the P-type structure, and thus the carrier recombination efficiency can be improved. 11 (2) PhCs with complex periodic structure are introduced. On the basis of single-period structure, the complex-period PhC structure can adjust the bandgap width, enhance the bandgap effect, limit the propagation of light in the horizontal direction, thus improve the vertical light extraction rate, 31,35 and further improve the performance of LEDs.…”

“…3,8 At present, many scholars have conducted research on GaN-based LEDs, and many schemes have been proposed, such as: (1) Improving the quantum well in the active region. [9][10][11][12][13] (2) Applying heterostructure capping. 8,[14][15][16] (3) Etching nanowires.…”

“…30 Wang et al inserted SiO 2 columns from the P layer to form single-period PhCs to improve LEE. 11 Ge et al adopted a square complex periodic semicircle structure and superimposed PhCs on the surface of a simple LED model. 31 Du et al added pyramidal triangular periodic PhCs to the LED model.…”

Enhancing light extraction efficiency of GaN-based light-emitting diodes with reticulated photonic crystals

“…3 However, the LEE remains extremely low due to the effects of total internal reflection (TIR) and Fresnel reflection. 4 Numerous light extraction techniques have been proposed and researched to address the aforementioned issues, such as surface roughing, 5 flip-chip, 6 photonic crystals (PhCs), 7,8 nanoarray surfaces, 9,10 nano-patterned sapphire substrates, 11 and others. In particular, the application of PhCs has received a lot of attention during the last decade as a light extractor to enhance the LEE through regulating the direction of light emissions.…”

Editorial of Special Issue “Nanostructured Light-Emitters”

“…They demonstrated that the emission intensity of the surface plasmon-based UV LEDs could be increased 70% higher than that of UV LEDs without using this approach. In another paper, Wang et al [6] investigated, both theoretically and experimentally, the enhancement in LEE and modulation bandwidth of flip-chip GaN LEDs using photonic crystal. This study shows a promising approach for achieving high-frequency visible light communication.…”