Truncated-inverted-pyramid light emitting diode geometry optimisation using ray tracing technique

GaAs pillar array-based light emitting diodes fabricated by metal-assisted chemical etching

“…Additionally, we attribute this enhanced efficiency to the light extraction improvement from the nanopillar array, allowing for more efficient photon escape as well as multiple scattering interactions, which reduce the probability of photon re-absorption. [32][33][34][35][36][37]45 The LED performance is expected to greatly improve by optimizing the pillar size, spacing, and height, as well as applying surface passivation and better metal contact schemes. A broader impact of this work relates to overcoming the "efficiency droop" phenomenon 44 by employing damagefree, high aspect ratio pillar-based LED designs in a wide range of compound semiconductors, particularly in InGaN green LEDs.…”

“…31 Although LEDs may be engineered with internal quantum yields approaching unity, 32 the emission of light from a planar and high refractive index active region into free space is limited by a narrow escape cone and, therefore, prone to internal reflection and re-absorption. 32,33 As such, exterior designs such as truncated inverted pyramid geometries 34,35 are widely used for minimizing internal reflection in commercial LEDs. In addition, surface texturing may be introduced, by way of "natural lithography" (combination of nano-sphere lithography and RIE) 36,37 or through the use of colloidal microlenses 38 as a highly effective route toward angular randomization of photon scattering, accommodating a dramatic enhancement of light extraction beyond the critical angle.…”

Light extraction study of LED using ray tracing computer simulation

“…In addition, most structure parameters changes reflect on the electronic properties of LEDs. One of the ways to increase extraction light efficiency is to use a device with specially shaped facets, for example, a truncated inverted pyramid (TIP) geometry LED [3,4]. Simple RT simulation in 2-d shows a pure geometrical effect -a significant difference in transmitted light power for regular shape and TIP LED (Fig.…”

Analysis of the Effect of Surface Texture in Light-Emitting Diodes Based on a Finite-Difference-Time-Domain Method

“…8,9) Despite the experimental success of surface patterning, the theoretical study still relies on ray-tracing, which can only deal with patterns much larger than a wavelength. [11][12][13] Although the research on photonic crystals frequently uses a Maxwell equation solver like the finite-difference-timedomain (FDTD) method, 14) most research focuses on a subwavelength structure that can hardly be realized in mass-production. Therefore, there is a necessity for more rigorous analysis in the scale domain between the sub-wavelength structure and the macro surface texture.…”