Enhancement of light extraction efficiency of ultraviolet light emitting diodes by patterning of SiO2 nanosphere arrays

Kim, B.J.; Jung, Hyung-Shik; Shin, Jang-Uk; Mastro, Michael A.; Eddy, Charles R.; Hite, Jennifer K.; Kim, S.H.; Bang, Joona; Kim, J.

doi:10.1016/j.tsf.2008.11.067

Cited by 28 publications

(21 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Their results show that textured p-GaN and indium tin oxide LEDs exhibit significant improvements as compared to conventional LEDs with disparity in electrical characteristics [137]. Kim et al reported that arrays of silica nanosphere monolayers that were spin-casted onto a polymer layer on top of a GaN surface can result in a hexagonal pattern of nanolenses that was shown to improve the light extraction efficiency of ultra violet LEDs by 23% [138]. An et al described the use of cone-shaped deep-pillar nanostructures to improve light extraction in Honeycomb-type vertical GaN light emitting diodes (VLEDs).…”

Section: Light Emitting Diodesmentioning

confidence: 99%

See 1 more Smart Citation

Bottom-Up Assembly and Applications of Photonic Materials

Zheng

Ravaine

2016

Crystals

View full text Add to dashboard Cite

Abstract:The assembly of colloidal building-blocks is an efficient, inexpensive and flexible approach for the fabrication of a wide variety of photonic materials with designed shapes and large areas. In this review, the various assembly routes to the fabrication of colloidal crystals and their post-assembly modifications to the production of photonic materials are first described. Then, the emerging applications of the colloidal photonic structures in various fields such as biological and chemical sensing, anti-reflection, photovoltaics, and light extraction are summarized.

show abstract

Section: Light Emitting Diodesmentioning

confidence: 99%

“…that arrays of silica nanosphere monolayers that were spin-casted onto a polymer layer on top of a GaN surface can result in a hexagonal pattern of nanolenses that was shown to improve the light extraction efficiency of ultra violet LEDs by 23% [138].…”

Section: Light Emitting Diodesmentioning

confidence: 99%

Bottom-Up Assembly and Applications of Photonic Materials

Zheng

Ravaine

2016

Crystals

View full text Add to dashboard Cite

show abstract

“…However, conventional LED chip geometries favor extracting light propagating parallel to the c-axis, and thus, the LEEs of AlGaN-based DUV LEDs with conventional chip geometries do not exceed 10%. 10,14,15 Conventional LEE-enhancing techniques-such as surface roughening, 16,17 substrate patterning 18 and incorporating anti-reflective coatings, 19 photonic crystals 20 and surface plasmonics 21 -are effective for GaInN-based visible LEDs but have a negligible effect on AlGaN DUV LEDs. 14 According to recent finite difference time domain calculations, the extraction of TM-polarized DUV light is .10 times lower than that of transverse electric (TE)-polarized light.…”

Section: Introductionmentioning

confidence: 99%

Overcoming the fundamental light-extraction efficiency limitations of deep ultraviolet light-emitting diodes by utilizing transverse-magnetic-dominant emission

et al. 2015

View full text Add to dashboard Cite

While the demand for deep ultraviolet (DUV) light sources is rapidly growing, the efficiency of current AlGaN-based DUV light-emitting diodes (LEDs) remains very low due to their fundamentally limited light-extraction efficiency (LEE), calling for a novel LEE-enhancing approach to deliver a real breakthrough. Here, we propose sidewall emission-enhanced (SEE) DUV LEDs having multiple light-emitting mesa stripes to utilize inherently strong transverse-magnetic polarized light from the AlGaN active region and three-dimensional reflectors between the stripes. The SEE DUV LEDs show much enhanced light output power with a strongly upward-directed emission due to the exposed sidewall of the active region and Al-coated selective-area-grown n-type GaN micro-reflectors. The devices also show reduced operating voltage due to better n-type ohmic contact formed on the regrown n-GaN stripes when compared with conventional LEDs. Accordingly, the proposed approach simultaneously improves optical and electrical properties. In addition, strategies to further enhance the LEE up to the theoretical optimum value and control emission directionality are discussed.

show abstract

“…Unfortunately, the dimensions of a photonic crystal designed for a GaN-based emitter are on the order of 250 nm [5], which is difficult to implement in a highvolume lithography process e although self-assembled approaches have proven promising [6]. A much simpler manufacturing approach is to roughen the GaN surface or the sapphire substrate (in a flip-chip configuration) to create an ensemble of sub-micron scattering sites [7].…”

Section: Introductionmentioning

confidence: 99%