High-efficiency InGaAlP/GaAs visible light-emitting diodes

Abstract

High-efficiency InGaAlP surface emission light emitting diodes (LEDs) have been successfully fabricated. Newly designed double-heterostructure LEDs with a GaAlAs current spreading layer were employed to expand the light emission area, which is necessary to take out the light efficiently. The external quantum efficiency was 1.5% at 620 nm orange light for an In0.5 (Ga0.8Al0.2)0.5P active layer LED. This LED is five times more efficient at 620 nm than that of the GaAlAs and GaAsP LEDs. 563 nm green electroluminescence, which is the shortest wavelength ever reported for InGaAlP LEDs, was also achieved with an In0.5(Ga0.5Al0.5)0.5P active layer.

Inorganic Semiconductors for Light‐emitting Diodes

“…A GaP current-spreading layer in an AlGaInP LED was reported by Kuo et al [26] and Fletcher et al [27,28]. AlGaAs current-spreading layers in AlGaInP LEDs were reported by Sugawara et al [29][30][31]. 16 For circular contact geometry, the thickness of the current spreading layer, t, results a current-spreading length L s given by [32] …”

“…The light extraction efficiency is defined as h extraction = # of photons emitted into free space per second # of photons emitted from active region per second = P/ h n ð Þ P int / h n ð Þ (1. 29) where P is the optical power emitted into free space. The extraction efficiency can be a severe limitation for high-performance LEDs.…”

Materials for Solid State Lighting

“…It is only recently, in the 1990's, that two significant advances occurred which finally made it possible to envision the use of LEDs for general purpose illumination. First, researchers at Hewlett Packard [2] and Toshiba [3] developed LEDs from the quaternary alloy AlGaInP lattice matched to GaAs , enabling high brightness LEDs in the red to amber with efficacies in the range of 10's of lumens/W. The second and perhaps more important development was the demonstration by Nakamura [4] that LEDs could be grown from GaN-based materials, which for the first time enabled bright emission in the blue and green.…”

“…Because this scheme depends on all visible light being emitted by the phosphors, there is no issue of color mixing. Rather, the drawbacks to this approach 3 reside with a lower efficiency due to the inherent energy loss in absorption of a UV photon and reemission of a lower energy visible photon. Further, the increased degradation of the packaging material and phosphor matrix material due to the high flux of UV radiation and high temperature is a serious issue.…”

Etching and smooth processing of GaAs surface based on the confined etchant layer technique

“…As compared to the semiconductor silicon material, it exhibits a very high forbidden bandwidth, high temperature resistance and radiation resistance (Aghion and Bronfin, 2000;Gray and Luan, 2002;Staiger et al, 2006). Through micro-nano manufacturing technology, GaAs wafer can be used to manufacture all kinds of light emitting devices, optical detector and integrated circuit (Sugawara et al, 1991;Sahin et al, 2015;Mikkelson and Tomasetta, 2003;Sadeghi et al, 2015). Micro-nano manufacturing technology can be divided into point-by-point processing method and batch processing of the microstructure.…”