High light-extraction GaN-based vertical LEDs with double diffuse surfaces

Ya Ju Lee, Hao Chung Kuo, Tien Chang Lu, Shing Chung Wang

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

High light-extraction (external quantum efficiency ∼40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 °C. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56% and 236% in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10-8 A at -5 V and a calculated external quantum efficiency of about 40%. The high scattering efficiency of double diffused surfaces could be responsible for the enhancement in the device light output power.

Original languageEnglish
Pages (from-to)1196-1201
Number of pages6
JournalIEEE Journal of Quantum Electronics
Volume42
Issue number12
DOIs
Publication statusPublished - 2006 Dec 1

Fingerprint

Light emitting diodes
light emitting diodes
Quantum efficiency
reflectors
quantum efficiency
potassium hydroxides
Anisotropic etching
Potassium hydroxide
augmentation
output
Growth temperature
Substrates
Tin oxides
Sapphire
Leakage currents
eutectics
indium oxides
Indium
Eutectics
tin oxides

Keywords

  • Double diffuse surfaces
  • GaN
  • Light-emitting diodes (LEDs)
  • Light-extraction efficiency

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

High light-extraction GaN-based vertical LEDs with double diffuse surfaces. / Lee, Ya Ju; Kuo, Hao Chung; Lu, Tien Chang; Wang, Shing Chung.

In: IEEE Journal of Quantum Electronics, Vol. 42, No. 12, 01.12.2006, p. 1196-1201.

Research output: Contribution to journalArticle

Lee, Ya Ju ; Kuo, Hao Chung ; Lu, Tien Chang ; Wang, Shing Chung. / High light-extraction GaN-based vertical LEDs with double diffuse surfaces. In: IEEE Journal of Quantum Electronics. 2006 ; Vol. 42, No. 12. pp. 1196-1201.
@article{8c4d9358bb14453580463579f0f99756,
title = "High light-extraction GaN-based vertical LEDs with double diffuse surfaces",
abstract = "High light-extraction (external quantum efficiency ∼40{\%}) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 °C. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56{\%} and 236{\%} in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10-8 A at -5 V and a calculated external quantum efficiency of about 40{\%}. The high scattering efficiency of double diffused surfaces could be responsible for the enhancement in the device light output power.",
keywords = "Double diffuse surfaces, GaN, Light-emitting diodes (LEDs), Light-extraction efficiency",
author = "Lee, {Ya Ju} and Kuo, {Hao Chung} and Lu, {Tien Chang} and Wang, {Shing Chung}",
year = "2006",
month = "12",
day = "1",
doi = "10.1109/JQE.2006.883468",
language = "English",
volume = "42",
pages = "1196--1201",
journal = "IEEE Journal of Quantum Electronics",
issn = "0018-9197",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "12",

}

TY - JOUR

T1 - High light-extraction GaN-based vertical LEDs with double diffuse surfaces

AU - Lee, Ya Ju

AU - Kuo, Hao Chung

AU - Lu, Tien Chang

AU - Wang, Shing Chung

PY - 2006/12/1

Y1 - 2006/12/1

N2 - High light-extraction (external quantum efficiency ∼40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 °C. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56% and 236% in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10-8 A at -5 V and a calculated external quantum efficiency of about 40%. The high scattering efficiency of double diffused surfaces could be responsible for the enhancement in the device light output power.

AB - High light-extraction (external quantum efficiency ∼40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 °C. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56% and 236% in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10-8 A at -5 V and a calculated external quantum efficiency of about 40%. The high scattering efficiency of double diffused surfaces could be responsible for the enhancement in the device light output power.

KW - Double diffuse surfaces

KW - GaN

KW - Light-emitting diodes (LEDs)

KW - Light-extraction efficiency

UR - http://www.scopus.com/inward/record.url?scp=33751382323&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33751382323&partnerID=8YFLogxK

U2 - 10.1109/JQE.2006.883468

DO - 10.1109/JQE.2006.883468

M3 - Article

AN - SCOPUS:33751382323

VL - 42

SP - 1196

EP - 1201

JO - IEEE Journal of Quantum Electronics

JF - IEEE Journal of Quantum Electronics

SN - 0018-9197

IS - 12

ER -