&lt;title&gt;45% quantum-efficiency light-emitting diodes with radial outcoupling taper&lt;/title&gt;

“…In 2000, Schmid et al [27] introduced an LED chip structure with lateral tapers whose external quantum efficiency was up to around 45%. InGaAs quantum well structure was grown by MBE techniques.…”

Section: (Iii) Geometrically Shaped Chipsmentioning

confidence: 99%

Fundamentals and Development Trends of High Power LED Packaging

2011

LED Packaging for Lighting Applications

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Electronic packaging is defined as a system assembly that does not include a chip or chips in terms of the system in packaging (SiP) definition. In general, an electronic packaging consists of four major functions: powering, signal distribution, mechanical protection, and thermal management. There are many types of electronic packaging, depending on the number of input/outputs (IOs) and applications. Electronic packaging can be in a single module or in a system and has been evolving rapidly. Many excellent books in packaging have been published [1,2] but there is no intention of reviewing them here. However, it is worthwhile to point out the rich development of electronic packaging by presenting a roadmap of single chip integrated circuit (IC) packaging development in Figure 2.1. Figure 2.2 presents the latest development in IC packaging: through silicon via (TSV) based three-dimensional (3D) packaging.Due to the introductory nature of this section, we only focus on a popular technology, flipchip, to show the evolution of the materials and processes involved. Figure 2.3 shows an IC flip-chip packaging on an FR4 board, demonstrating a two-level packaging, in a typical control board for an engine control system. Figure 2.4 shows a cross-sectional view of a flip-chip packaging, showing clearly the local features of flip-chip interconnects. In this figure, the passivation layer provides the protection for the silicon chip which is done on the wafer level. Solder mask is a polymer used to protect LED Packaging for Lighting Applications: Design, Manufacturing and Testing, First Edition. Sheng Liu and Xiaobing Luo.

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“…However, until recently, the overall ("wallplug") efficiency of standard LEDs was typically as low as 8 to 20 %, limited by the total internal reflection at the interface between a high-index semiconductor material (n > 3) and air (n = 1) or epoxy (n ~ 1.5). Nevertheless, much better efficiencies (some superior to 50 %) [2][3][4][5][6][7] have been achieved with electrically-pumped LEDs in the past few years. This progress is essentially due to a better engineering of the optics of the devices.…”

Section: Introductionmentioning

confidence: 99%

Recent results and latest views on microcavity LEDs

et al. 2004

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We are progressively approaching the physical limits of microcavity LEDs (MC-LEDs) for high brightness, high efficiency LEDs. They are promising high efficiency devices and they offer the very attractive prospect of full planar fabrication process. However, to compete with other high efficiency LED schemes, they need to approach or surpass the 50 % efficiency mark. We first explore the limits of planar MC-LEDs in both the GaAlInAsP and GaInAlN materials systems, and show that the single-step extraction limit is in the 40 % range at best, depending on the materials system used, with the largest part of the non-extracted light being emitted into guided modes. The waveguided light can itself be extracted by photon recycling, when the internal quantum efficiency is high. Otherwise, another extraction scheme for that light is provided by various photonic-crystal-assisted extraction schemes. Simple photonic crystals (PCs) appear to lack the omnidirectional extraction properties required. However, more rotation-invariant PCs like Archimedean tilings allow to obtain such extraction with added efficiencies already in the 10% range. We discuss the further improvements to such structures.

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<title>45% quantum-efficiency light-emitting diodes with radial outcoupling taper</title>

Cited by 12 publications

References 6 publications

Inorganic Semiconductors for Light‐emitting Diodes

Inorganic Semiconductors for Light‐emitting Diodes

Fundamentals and Development Trends of High Power LED Packaging

Recent results and latest views on microcavity LEDs

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