GaN-based light-emitting diode with textured indium tin oxide transparent layer coated with Al2O3 powder

Kim, T. K.; Kim, S. H.; Yang, Seong Seok; Son, Jae-Kwon; Lee, K. H.; Hong, Y. G.; Shim, Kyu–Hwan; Yang, J.; Lim, Kee Young; Bae, Seong Jun; Yang, Gye Mo

doi:10.1063/1.3120222

Cited by 36 publications

(18 citation statements)

References 12 publications

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“…Various approaches have been adopted to extract the trapped light in the LED, and great efforts have been made in incorporating photonic crystal (PhC) into GaN-based LED to improve the light extraction [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Shallow etched PhC gratings are employed on the surface of different materials, such as GaN [1, 2,4], indium tin oxide (ITO) [9,10], or thin polymer layer [11,12]. In most publications, the strategy of using a PhC grating mainly relies on Bragg diffraction of the trapped guided modes from the LEDs.…”

Section: Introductionmentioning

confidence: 99%

Lattice constant effects of photonic crystals on the extraction of guided mode of GaN based light emitting diodes

Bei

Kang

et al. 2010

Sci. China Technol. Sci.

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We have fabricated a series of square-lattice hole photonic crystal (2PhC) arrays simultaneously at the un-current injection region on a special sample of GaN based light emitting diode (LED) by using focus ion beam milling (FIBM). The lattice constants of the 2PhC arrays vary from 230 to 1500 nm, while the 2PhC arrays have a constant area of about 9 μm ×18 μm and a fixed depth of 150±10 nm which approaches but does not penetrate the active layer. Microscopic electroluminescence images and spectral measurements consistently confirm that the top emitting intensities from different 2PhCs are all enhanced compared with the unpatterned region. It is demonstrated that the output coupling of propagating guided modes is realized by the diffracted transmission of the 2PhCs. The enhancement factors of the guided modes compared with the unpatterned region are plotted as function of the lattice constant. It is found that the highest enhancements for the extraction of guided modes were obtained for the lattice constant of 230 and 460 nm of 2PhCs. The results are discussed by the two-dimensional rigorous coupled wave analysis (RCWA). photonic crystal, guided modes, lattice pitches, GaN-based light emitting diodes Citation: Fu X X, Zhang B, Kang X N, et al. Lattice constant effects of photonic crystals on the extraction of guided mode of GaN based light emitting diodes.

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Section: Introductionmentioning

confidence: 99%

Lattice constant effects of photonic crystals on the extraction of guided mode of GaN based light emitting diodes

Bei

Kang

et al. 2010

Sci. China Technol. Sci.

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“…There are several methods to maintain the angle of the emitted light from the active region within the critical angle, such as changing the LED chip shape, reducing the thickness of the film, and roughening the surface [10,11]. Previous researchers [12][13][14][15][16][17][18] have reported about Ni film as an interlayer in LED structure to improve Ohmic contact and also treated-surface layers to increase the light output of GaN-based LEDs. Most of them focus on surface-treated GaN, ITO, and sapphire layers, while very few report [6,11] on treated-ZnO layers to increase the light output of GaN-based LEDs.…”

Section: Introductionmentioning

confidence: 97%

Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

et al. 2012

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This letter presents a holographic photonic crystal (H-PhC) Al-doped ZnO (AZO) transparent Ohmic contact layer on p-GaN to increase the light output of GaN-based LEDs without destroying the p-GaN. The operating voltage of the PhC LEDs at 20 mA was almost the same as that of the typical planar AZO LEDs. While the resultant PhC LED devices exhibited significant improvements in light extraction, up to 1.22 times that of planar AZO LEDs without PhC integration. Temperature dependence of the integrated photoluminescence intensity indicates that this improvement can be attributed to the increased extraction efficiency due to the surface modification. These results demonstrate that the surface-treated AZO layer by H-PhCs is suitable for fabricating high-brightness GaN-based LEDs.Singapore EDB [NRF2008EWT-CERP002-041, NUS R284-000-081-592]; Du Pont Apoll

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“…Various ordered and disordered ITO structures have been fabricated by wet chemical etching or inductively coupled plasma reactive ion etching (ICP-RIE) processes. [3][4][5][6][7][8] Wet etching has a good input-output ratio but lacks controllability in achieving designed structure profiles. The process of ICP-RIE is an effective method for ITO etching with a high etching rate and good selectivity; however, the incident direction of the reactive ions is always normal to the sample, which does not provide flexibility for controlling the geometry of ITO patterns.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of indium tin oxide bump/pit structures on GaN-based light emitting diodes

Liu

Wang

Yang

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In the past several decades, significant progress has been made to improve the performance of semiconducting light emitting diodes (LEDs), which has resulted in a wide number of applications for LEDs in the information and energy fields. However, light extraction efficiency is limited due to remarkable total internal reflection on the device's surface due to the large refractive index of GaN and indium tin oxides (ITO). In this work, ITO bump and pit patterns were fabricated on the LED surface using an ion beam etching method via metal or resist masks, respectively. By changing the incident angle of the ion beam and the material of the masks, the effects of faceting and redeposition can be properly controlled, resulting in well-controlled manipulation of the shape of the fabricated bump/pit structures. By altering the etching time, the over-etched structures have a much smoother surface compared with the under-etched/in-etched structures. These bump/pit structures could have potential applications in LED light emitting enhancement and optical devices.

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GaN-based light-emitting diode with textured indium tin oxide transparent layer coated with Al2O3 powder

Cited by 36 publications

References 12 publications

Lattice constant effects of photonic crystals on the extraction of guided mode of GaN based light emitting diodes

Lattice constant effects of photonic crystals on the extraction of guided mode of GaN based light emitting diodes

Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

Fabrication of indium tin oxide bump/pit structures on GaN-based light emitting diodes

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