Improvement of InGaN-GaN light-emitting diodes with surface-textured indium-tin-oxide transparent ohmic contacts

Pan, Shyi-Ming; Tu, R. C.; Fan, Yu-Mei; Yeh, Ruey-Chyn; Hsu, Jung−Tsung

doi:10.1109/lpt.2003.809985

Cited by 58 publications

(11 citation statements)

References 13 publications

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“…For instance, surface texturing combining with ITO transparent contact has been demonstrated [31]- [32] . ITO transparent electrode together with vertical electrode [33] increasing the light output power by 1.75 times compared to conventional NiAu lateral electrode LED was also reported.…”

Section: Resultsmentioning

confidence: 99%

Enhancing the light extraction efficiency of GaN-based LEDs

Niu

et al. 2007

SPIE Proceedings

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GaN-based light-emitting diode (LED) has been widely used in recent years, and tremendous progress has been achieved in GaN-based semiconductor materials and relevant process. However, owing to the large refractive index contrast between GaN-based semiconductor materials and air, light can be easily totally internally reflected at the semiconductor/air interface, and the critical angle for light to escape from the semiconductor is small. Therefore, the light extraction efficiency for GaN-based LED is still low and needs improving. Some of the leading approaches to enhance light extraction efficiency of GaN-based LED such as surface texturing or roughening, omnidirectional reflectors, photonic crystals, laser liftoff, transparent electrode, patterned substrate and so on are introduced in detail. For each approach, how the variation in device structure or material improves the light extraction efficiency is analyzed thoroughly. At last, some of mentioned approaches that are promising are evaluated and viewed briefly.

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Section: Resultsmentioning

confidence: 99%

Enhancing the light extraction efficiency of GaN-based LEDs

Niu

et al. 2007

SPIE Proceedings

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“…As well known, the large difference in the refractive index between the GaN(2.40) and air(1) caused a narrow escape cone for the light in GaN crystal. One most used method is roughness or texture on interfaces, such as the patterned sapphire substrate (PSS) recently [1], [2], [3], [4] , and the increasing efficiency of PSS LED is considered as a consequence of the light scattering by the PSS. Huang, etc developed the side wall shaping and truncated inverted pyramid (TIP) shaping technology to increase the external quantum efficiency (EQE) of GaN LED [5], [6] .…”

Section: Introductionmentioning

confidence: 99%

The effects of sapphire substrates processes to the LED efficiency

et al. 2007

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We investigate the relation between the thickness of sapphire substrates and the extraction efficiency of LED. The increasing about 5% was observed in the simulations and experiments when the sapphire thickness changed from 100um to 200um. But the output power increasing is inconspicuous when the thickness is more than 200um. The structure on bottom face of sapphire substrates can enhance the extraction efficiency of GaN-based LED, too. The difference of output power between the flip-chip LED with smooth bottom surface and the LED with roughness bottom surface is about 50%, where only a common sapphire grinding process is used. But for those LEDs grown on patterned sapphire substrate the difference is only about 10%. Another kind of periodic pattern on the bottom of sapphire is fabricated by the dry etch method, and the output of the back-etched LEDs is improved about 50% than a common case.

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“…In recent years, the tremendous progress in the technologies of GaN-based epitaxial growth and device processes have been giving us the chances to fabricate light-emitting diodes (LEDs), laser diodes (LDs), and high-power/highfrequency electronic devices, and their performances are improving continuously. [1][2][3][4] In particular, GaN-based LEDs with characteristics of smallness, lightweight, and long lifetime are widely applied to LCD backlight, full color displays, and traffic displays.…”

Section: Introductionmentioning

confidence: 99%

GaN-Based Light-Emitting Diode with Indium–Tin–Oxide and Vertical Electrode

Kim¹

2005

Jpn. J. Appl. Phys.

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A sapphire-etched vertical-electrode nitride semiconductor (SEVENS) light-emitting diode (LED) is fabricated by a selective wet-etching technique. The SEVENS-LED has an indium–tin–oxide (ITO) transparent metal electrode (TME) and a sapphire via hole. The SEVENS-LED exhibits excellent device performances compared with a lateral-electrode (LE) GaN-based LED formed on a sapphire substrate. The light-output power of the SEVENS-LED is ∼7 mW at a 20 mA junction current, which means 13% external quantum efficiency (EQE). The electrostatic discharge (ESD) test shows excellent ESD characteristics of the SEVENS-LED compared with those of the ITO LE-LED. The reverse ESD amplitude of SEVENS-LED is approximately 200 V, which is two times higher than that (∼100 V) of the ITO LE-LED. These improvements of ESD properties are attributed to the change of the lateral electrode to a vertical electrode, without requiring the transfer of the sapphire substrate to a conducting substrate.

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Improvement of InGaN-GaN light-emitting diodes with surface-textured indium-tin-oxide transparent ohmic contacts

Cited by 58 publications

References 13 publications

Enhancing the light extraction efficiency of GaN-based LEDs

Enhancing the light extraction efficiency of GaN-based LEDs

The effects of sapphire substrates processes to the LED efficiency

GaN-Based Light-Emitting Diode with Indium–Tin–Oxide and Vertical Electrode

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