Optical cavity effects in InGaN/GaN quantum-well-heterostructure flip-chip light-emitting diodes

Shen, Yun‐Hwei; Wierer, Jonathan J.; Krames, Michael R.; Ludowise, M. J.; Misra, M.; Ahmed, Farid; Kim, Andy Y.; Mueller, Gerd; Bhat, J.; Stockman, S. A.; Martin, P.

doi:10.1117/12.520571

Cited by 16 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this example, our results indicate that a maximum enhancement is achieved when the barrier thickness is around 600nm, while a minimum is obtained 50nm below the grating. In modern LEDs, the QW is often positioned at approximately 3/4 wavelengths from the top mirror to optimize the emission rate [22], [23]. For a 450nm wavelength and a GaN refractive index of 2.5 [20], this corresponds to approximately 130nm.…”

Section: Resultsmentioning

confidence: 99%

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Sadi

Oksanen

Tulkki

2014

IEEE J. Quantum Electron.

View full text Add to dashboard Cite

Recent experimental work has demonstrated that the light extraction enhancement due to scattering by a metallic nano-grating in an InGaN/GaN quantum well (QW) structure can be improved significantly by burying the grating in a dielectric, such as polyvinyl alcohol (PVA). In this paper, we employ the fluctuational electrodynamics method to investigate the origin of this improvement and to provide guidelines on how to optimize emission efficiency in these structures. Our results show that metallic grating diffracts efficiently the high-intensity PVA resonances trapped in the structure, because of the large permittivity contrast between the metal and semiconductor, providing the reported exceptional enhancement for s-polarization. We also study the effect of two important physical factors in the enhancement: 1) the thickness of the GaN barrier separating the QW from the grating and 2) the thickness of the InGaN QW. Results reveal that the enhancement efficiency can be maintained even when the QW is not in the near field of the grating, for a QW-grating separation of up to 1 µm. This is in contrast to plasmonic structures, where enhancement strongly decreases as the separation is increased. However, the enhancement factor can also vary strongly at the local level in smaller spatial intervals. Results also show that the enhancement significantly decreases with the QW thickness due to the losses in the QW.Index Terms-GaN quantum well (QW) light-emitting structures, diffraction gratings, luminescence enhancement, fluctuational electrodynamics method.

show abstract

Section: Resultsmentioning

confidence: 99%

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Sadi

Oksanen

Tulkki

2014

IEEE J. Quantum Electron.

View full text Add to dashboard Cite

show abstract

“…Conventional flip chips (CFC or FC) are made similarly as conventional chips, except that for both the ncontact and the p-contact an interconnect metallization is applied for soldering or Au-Au die attach to a substrate. C ext is dominated by an optical cavity effect between the highly reflective p-contact and the light emission from the quantum wells as the distance between them is in the order of an optical wavelength [3]. As a result the angular radiation pattern can be tuned for maximum emission into a silicone encapsulation, resulting in >60% extraction efficiency.…”

Section: Led Chip Designmentioning

confidence: 99%

“…2 Better extraction efficiency using Thin Film Flip Chip devices. 3 Lower thermal resistance of Flip Chip designs. 4 Better optical coupling efficiency with Flip Chip designs.…”

Section: Introductionmentioning

confidence: 99%

Performance and trends of high power light emitting diodes

et al. 2007

View full text Add to dashboard Cite

We will discuss the performance, progress and trend of High Power Light Emitting Diodes (HP-LEDs), suitable for high luminance applications like micro-display projection, car headlamps, spot lamps, theatre lamps, etc. Key drivers for the high luminance applications are LED parameters such as internal quantum efficiency, extraction efficiency, drive current, operating temperature and optical coupling efficiency, which are important for most applications as they also enable higher lumen/$ ratios. Historical progress, prospects for improving these parameters and potential optical luminance enhancement methods to meet the demands for the various illumination applications are presented.

show abstract

“…9,10 When placing a QW at optimum distance from the mirror, directional enhancement of the light output has been observed for visible emission wavelengths. [10][11][12][13] In this letter, the performance of near-UV emitting InGaN/AlInGaN LEDs and the effect of different placement of the wells on the output power are reported.…”

Section: Introductionmentioning

confidence: 98%

Enhanced efficiency of near-UV emitting LEDs for solid state lighting applications

Zhu

Corbett²,

Roycroft³

et al. 2007

SPIE Proceedings

View full text Add to dashboard Cite

The performance of a series of near-UV (∼385 nm) emitting LEDs, consisting of high efficiency InGaN/AlInGaN QWs in the active region, was investigated. Significantly reduced roll-over of efficiency at high current density was found compared to InGaN/GaN LEDs emitting at a similar wavelength. The importance of optical cavity effects in flip-chip geometry devices has also been investigated. The light output was enhanced by more than a factor of 2 when the lightemitting region was located at an anti-node position with respect to a high reflectivity current injection mirror. A power of 0.49 mW into a numerical aperture of 0.5 was obtained for a junction area of 50 µm in diameter and a current of 30 mA, corresponding to a radiance of 30 W/cm 2 /str.

show abstract

Optical cavity effects in InGaN/GaN quantum-well-heterostructure flip-chip light-emitting diodes

Cited by 16 publications

References 0 publications

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Performance and trends of high power light emitting diodes

Enhanced efficiency of near-UV emitting LEDs for solid state lighting applications

Contact Info

Product

Resources

About