Enhanced Light Extraction Efficiency of GaN-Based LEDs With 3-D Colloidal-Photonic-Crystal Bottom Reflector

Huang, Kai‐Lin; Chang, Heng-Jui; Ho, Chong-Lung; Wu, Meng‐Chyi

doi:10.1109/lpt.2012.2202284

Cited by 24 publications

(13 citation statements)

References 14 publications

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“…3D colloidal PC has been adopted as a back reflector in GaN‐based LED. The light output power of the LED increased by 155% compared to that of a conventional LED . However, the only shortcoming of 3D colloidal PC‐based back reflector lies in the strong angle dependence of the incident light.…”

Section: Introductionmentioning

confidence: 99%

Layer‐by‐Layer Approach to (2+1)D Photonic Crystal Superlattice with Enhanced Crystalline Integrity

Zhang

Xiong

Shan

et al. 2015

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Large-area polystyrene (PS) colloidal monolayers with high mechanical strength are created by a combination of the air/water interface self-assembly and the solvent vapor annealing technique. Layer-by-layer (LBL) stacking of these colloidal monolayers leads to the formation of (2+1)D photonic crystal superlattice with enhanced crystalline integrity. By manipulating the diameter of PS spheres and the repetition period of the colloidal monolayers, flexible control in structure and stop band position of the (2+1)D photonic crystal superlattice has been realized, which may afford new opportunities for engineering photonic bandgap materials. Furthermore, an enhancement of 97.3% on light output power of a GaN-based light emitting diode is demonstrated when such a (2+1)D photonic crystal superlattice employed as a back reflector. The performance enhancement is attributed to the photonic bandgap enhancement and good angle-independence of the (2+1)D photonic crystal superlattice.

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Section: Introductionmentioning

confidence: 99%

Layer‐by‐Layer Approach to (2+1)D Photonic Crystal Superlattice with Enhanced Crystalline Integrity

Zhang

Xiong

Shan

et al. 2015

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“…Qualitatively, it is observed that the patterned LED has an average increase of the intensity of 30% when compared with its unpatterned counterpart. Although, this improvement is comparatively low relative to that of the extraction observed from other methods [13], [17], [31], [34], our process can be considered complementary to the existing methods and a means to achieve additional performance improvements.…”

Section: Characterization and Resultsmentioning

confidence: 84%

“…On the other hand, a major source of optical output power loss is due to light being trapped within the materials due to the optical properties,which affects the light extraction efficiency of the LED. Various methods, such as surface roughening [8], [9], [10], [11], patterned substrates [12], [13], [14], integration of DBRs and photonic crystals [15], [16], [17] are being utilized by research groups to improve LED extraction efficiency [18]. These methods add additional complexities to the fabrication process of the LEDs.…”

mentioning

confidence: 99%

“…The propagation of light through a PhC lattice can be engineered by choosing the appropriate geometries and critical parameters of the crystal (lattice parameter, index of refraction, etc.). Groups have utilized dielectric PhC structures (one [15], two [23] and three [17] dimensional) as optical elements of the LED structure to increase the light extraction from the device [14], [30], [24], [18]. Another use of PhC lattice structures is in the creation of diffraction elements.…”

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confidence: 99%

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Improvement in the Light Extraction of Blue InGaN/GaN-Based LEDs Using Patterned Metal Contacts

Kadiyala

Lee

Rodak

et al. 2014

IEEE J. Electron Devices Soc.

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We demonstrate a method to improve the light extraction from an LED using photonic crystal (PhC)-like structures in metal contacts. A patterned metal contact with an array of Silicon Oxide (SiO x ) pillars (440 nm in size) on an InGaN/GaNbased MQW LED has shown to increase output illumination uniformity through experimental characterization. Structural methods of improving light extraction using transparent contacts or dielectric photonic crystals typically require a tradeoff between improving light extraction and optimalelectrical characteristics.The method presented here provides an alternate solution to provide a 15% directional improvement (surface normal) in the radiation profile and ∼ 30% increase in the respective intensity profile without affecting the electrical characteristics of the device. Electron beam patterning of hydrogen silesquioxane (HSQ), a novel electron beam resist is used in patterning these metal contacts. After patterning, thermal curing of the patterned resist is done to form SiO x pillars. These SiO x pillars aid as a mask for transferring the pattern to the p-metal contact. Electrical and optical characterization results of LEDs fabricated with and without patterned contacts are presented. We present the radiation and intensity profiles of the planar and patterned devices extracted using Matlab-based image analysis technique from 200 μm (diameter) circular unpackaged LEDs.Index Terms-Electron beam lithography (EBL), light emitting diode (LED), patterning, photonic crystal (PC), hydrogen silesquioxane (HSQ).

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“…[1,2]. Moreover, it is well known that the presence of spontaneous and piezoelectric polarizations at the GaN/AlGaN interface allows a large two-dimensional electron gas (2DEG) and remarkable electron transport behavior for heterostructure field-effect transistors (HFETs) [3].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen sensing characteristics of a Pt/AlGaN/GaN heterostructure field-effect transistor (HFET) prepared by sensitization, activation, and electroless plating (EP) approaches

Chen

Liu

et al. 2015

Sensors and Actuators B: Chemical

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Enhanced Light Extraction Efficiency of GaN-Based LEDs With 3-D Colloidal-Photonic-Crystal Bottom Reflector

Cited by 24 publications

References 14 publications

Layer‐by‐Layer Approach to (2+1)D Photonic Crystal Superlattice with Enhanced Crystalline Integrity

Layer‐by‐Layer Approach to (2+1)D Photonic Crystal Superlattice with Enhanced Crystalline Integrity

Improvement in the Light Extraction of Blue InGaN/GaN-Based LEDs Using Patterned Metal Contacts

Hydrogen sensing characteristics of a Pt/AlGaN/GaN heterostructure field-effect transistor (HFET) prepared by sensitization, activation, and electroless plating (EP) approaches

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