Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode

Seo, Tae Hoon; Lee, Kang Jea; Oh, Tae Su; Lee, Yong Seok; Jeong, Hyun; Park, Ah Hyun; Kim, Hun; Choi, Young Ran; Suh, Eun‐Kyung; Cường, Trần Việt; Phạm, Việt Hùng; Chung, Jin Suk; Kim, Eui Jung

doi:10.1063/1.3601462

Cited by 47 publications

(27 citation statements)

References 18 publications

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“…Note that, prior to the graphene transfer, the surfaces of the GaN wafers were cleaned with acetone, isopropyl alcohol, H 2 SO 4 :HCl (1:1) solutions, a buffered oxide etchant, and deionized water. The detailed synthesis of graphene by the CVD method and transfer techniques can be found elsewhere [24][25][26][27]36] (also shown in Fig. S1 in the Electronic Supplementary Material (ESM)).…”

Section: Methodsmentioning

confidence: 99%

“…Accordingly, Chandramohan et al [23] showed that the specific contact resistance of a graphene contact formed on heavily Mg-doped p-GaN was as large as ~10 -1 Ω·cm 2 . To overcome this poor p-Ohmic contact, a hybrid-type contact combining graphene with indium-tin-oxide islands [24], Au nanoparticles [25], Ag nanowires [26], and Ag nanocluster [27] has been introduced by our groups.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, its good electrical conductivity and excellent optical transparency across the entire spectrum of wavelengths of graphene made it a promising candidate for use as a transparent contact in optoelectronic devices such as solar cells [15][16][17][18] and light-emitting diodes (LEDs) [19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

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Graphene-GaN Schottky diodes

et al. 2014

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The electrical characteristics of graphene Schottky contacts formed on undoped GaN semiconductors were investigated. Excellent rectifying behavior with a rectification ratio of ~10 7 at ±2 V and a low reverse leakage current of 1.0 × 10 -8 A/cm 2 at -5 V were observed. The Schottky barrier heights, as determined by the thermionic emission model, Richardson plots, and barrier inhomogeneity model, were 0.90, 0.72, and 1.24 ± 0.13 eV, respectively. Despite the predicted low barrier height of ~0.4 eV at the graphene-GaN interface, the formation of excellent rectifying characteristics with much larger barrier heights is attributed to the presence of a large number of surface states (1.2 × 10 13 states/cm 2 /eV) and the internal spontaneous polarization field of GaN, resulted in a significant upward surface band bending or a bare surface barrier height as high as of 2.9 eV. Using the S parameter of 0.48 (measured from the work function dependence of Schottky barrier height) and the mean barrier height of 1.24 eV, the work function of graphene in the Au/graphene/GaN stack could be approximately estimated to be as low as 3.5 eV. The obtained results indicate that graphene is a promising candidate for use as a Schottky rectifier in GaN semiconductors with n-type conductivity.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Graphene-GaN Schottky diodes

et al. 2014

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“…12 Other solutions include using interlayers of thin metal 13,14 or ITO nanodots. 15 Nevertheless, these attempts were all at the expense of losing transparency (e.g., merely 78% for 1 nm Ni/1 nm Au/monolayer graphene). 14 We note that optical transmission is ultra important for LEDs.…”

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confidence: 99%

Graphene transparent electrodes grown by rapid chemical vapor deposition with ultrathin indium tin oxide contact layers for GaN light emitting diodes

Deng

et al. 2013

Applied Physics Letters

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By virtue of the small active volume around Cu catalyst, graphene is synthesized by fast chemical vapor deposition (CVD) in a cold wall vertical system. Despite being highly polycrystalline, it is as conductive and transparent as standard graphene and can be used in light emitting diodes as transparent electrodes. 7-10 nm indium tin oxide (ITO) contact layer is inserted between the graphene and p-GaN to enhance hole injection. Devices with forward voltage and transparency comparable to those using traditional 240 nm ITO are achieved with better ultraviolet performances, hinting the promising future for application-oriented graphene by rapid CVD. V

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“…Many researches have tried to solve this problem by using spreading layers [17][18][19]. Until now, indium-tin-oxide (ITO) has been used broadly as a current spreading layer for its transparency and low resistance [20][21][22]. Although the ITO in the LED device makes current spread widely toward the active region, however, the non-uniformity of current spreading has not been solved completely [23,24].…”

Section: Introductionmentioning

confidence: 99%

Effects of Current Spreading in GaN-based Light-emitting Diodes Using ITO Spreading Pad

Kim¹,

Kım²,

Park³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

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Abstract-In conventional LEDs, a mesa-structure is usually used and it causes the current to be overcrowded in a specific region. We propose a novel structure of GaN-based LED to overcome this problem. In order to distribute the current in an active region, a spreading pad is inserted at the p-type region in the GaN based LED device. The inserted spreading pad helps the current flow because it is more conductive than the p-type GaN layer. By performing electrical and optical simulations, the effects of the spreading pad insertion are confirmed. The results of electrical simulation show that the current spreads more uniformly and more radiative recombination is produced as well. Moreover, from the optical simulation, it is revealed that the ITO is less absorptive material than p-GaN if the condition of specific wavelength sources is satisfied. Considering all of the results, we can conclude that the luminescent power is enhanced by the spreading pad.

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Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode

Cited by 47 publications

References 18 publications

Graphene-GaN Schottky diodes

Graphene-GaN Schottky diodes

Graphene transparent electrodes grown by rapid chemical vapor deposition with ultrathin indium tin oxide contact layers for GaN light emitting diodes

Effects of Current Spreading in GaN-based Light-emitting Diodes Using ITO Spreading Pad

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