High-output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy

Tadatomo, Kazuyuki; Okagawa, Hiroaki; Ohuchi, Youichiro; Tsunekawa, Takashi; Kudo, Hiromitsu; Sudo, Yasuhide; Kato, Munehiro; Taguchi, Tsunemasa

doi:10.1117/12.513288

Cited by 8 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The heat generated by light absorption inside the LED chip is assumed to be included in the q ˙term. The values of the external quantum efficiency ͑ int ϫ ext ͒, as obtained in the literature, 18,20 are between 13 and 43%. Thus, in the present study, int ϫ ext = 25% was selected.…”

Section: Numerical Modelmentioning

confidence: 95%

A Numerical Study of Thermal and Electrical Effects in a Vertical LED Chip

Hwu

Chen²,

et al. 2010

J. Electrochem. Soc.

View full text Add to dashboard Cite

The influence of the size of an n-electrode and a current blocking layer (CBL) on the thermal and electrical characteristics of a vertical-injection GaN-based light emitting diode (LED) chip is investigated by numerical simulation. The predicted forward voltages are quite consistent with previous experimental data. The coupled thermal and electrical effects affect the performance of a LED chip. For cases without a CBL, the variation in current density and temperature distributions in the active layer, and the forward voltage and Joule heating percentage of the LED chip increase as the n-electrode width (L) decreases. The current crowding and temperature of the hot spot are very significant, although the wall-plug efficiency (WPE) is the highest one obtained for L=100μm . The better width of the n-electrode in terms of the uniformity of temperature, current density distribution, WPE, and forward voltage may be the case where L=200μm . The insertion of a CBL into a 600×600μm chip leads to greater uniformity in the distribution of the current density in the effective light-emitting area when L=500μm . A more uniform temperature distribution in the active layer occurs when L=200μm , while the case when L=300μm has the maximum WPE.

show abstract

Section: Numerical Modelmentioning

confidence: 95%

A Numerical Study of Thermal and Electrical Effects in a Vertical LED Chip

Hwu

Chen²,

et al. 2010

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…The characteristic inclined crystallographic facets resulting from wetetching can facilitate superior light extraction efficiency. 8,9 Moreover, wet-etching causes less damage to the substrate than dry etching does. Recently, much work has been done to study the growth of LEDs on PSSs with dot-patterns.…”

Section: Introductionmentioning

confidence: 99%

Growth and Characterizations of GaN-Based LEDs Grown on Wet-Etched Stripe-Patterned Sapphire Substrates

Hwang

Lau

2008

Journal of Elec Materi

View full text Add to dashboard Cite

The material and electrical properties of GaN-based light-emitting diodes (LEDs) grown on wet-etched stripe-patterned substrates were investigated. Footprint-like patterns, located directly above the inclined groove sidewalls, were found on the as-grown LED surface. Cross-sectional transmission electron microscopy (TEM) showed that ÔtumorÕ-like structures with poor crystal quality were initiated on the inclined sidewalls, seeding dislocation bundles in the subsequently grown crystal. The high dislocation density slowed down the growth above the inclined sidewall, resulting in the uneven morphology. The fabricated devices showed over 30% enhancement in light output power as a result of improvements in both internal and extraction efficiencies.

show abstract

“…Due to the substantial difference in refractive index between the epitaxial GaN film and air, the relatively small total internal reflection angle leads to poor LEE OE7 . Hence, the patterns can serve as scattering centers for redirecting the guided light into a randomized distribution of angles that will enable multiple entries of photons into the escape cone OE8; 9 . This means that, in face-up LED structures, the light scattering effect from the patterns explains very well the enhanced top-surface light output power (LOP) and LEE OE10; 11 .…”

Section: Introductionmentioning

confidence: 99%

Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

Dongxue

Liu

et al. 2016

J. Semicond.

View full text Add to dashboard Cite

The effect of patterned sapphire substrate (PSS) on the top-surface (P-GaN-surface) and the bottom-surface (sapphire-surface) of the light output power (LOP) of GaN-based LEDs was investigated, in order to study the changes in reflection and transmission of the GaN-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of GaN-based LEDs, which are prepared on patterned sapphire substrates (PSS-LEDs). Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates (CSS-LEDs). A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-GaN interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency (LEE) can be further enhanced by integrating the method of PSS and flip-chip structure design.

show abstract

High-output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy

Cited by 8 publications

References 0 publications

A Numerical Study of Thermal and Electrical Effects in a Vertical LED Chip

A Numerical Study of Thermal and Electrical Effects in a Vertical LED Chip

Growth and Characterizations of GaN-Based LEDs Grown on Wet-Etched Stripe-Patterned Sapphire Substrates

Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

Contact Info

Product

Resources

About