Dislocation analysis in homoepitaxial GaInN/GaN light emitting diode growth

Detchprohm, Theeradetch; Xia, Yong; Xi, Y.; Zhu, Mingwei; Zhao, Wei; Li, Y.; Schubert, E. Fred; Liu, L.; Tsvetkov, D.; Hanser, Drew; Wetzel, Christian

doi:10.1016/j.jcrysgro.2006.10.129

Cited by 28 publications

(46 citation statements)

References 9 publications

(11 reference statements)

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“…With GaN bulk crystal growth still in its infancy, most of the bulk substrates are based on thick GaN layers grown by hydride vapor phase epitaxy (HVPE) separated from foreign substrates. [6][7][8] These free-standing GaN layers grown by HVPE offer an excellent crystal quality and low threading dislocation densities 9,10 with low AFM roughness. However, the fast HVPE growth of thick layers, even with homogeneously high crystal quality, on MOVPE templates introduces defects and pits which lead to a macroscopically rough surface.…”

Section: Introductionmentioning

confidence: 99%

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

et al. 2014

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We demonstrate the strong influence of GaN substrate surface morphology on optical properties and performance of light emitting devices grown on freestanding GaN. As-grown freestanding HVPE GaN substrates show excellent AFM RMS and XRD FWHM values over the whole area, but distinctive features were observed on the surface, such as macro-pits, hillocks and facets extending over several millimeters. Electroluminescence measurements reveal a strong correlation of the performance and peak emission wavelength of LEDs with each of these observed surface features. This results in multiple peaks and non-uniform optical output power for LEDs on as-grown freestanding GaN substrates. Removal of these surface features by chemical mechanical polishing results in highly uniform peak wavelength and improved output power over the whole wafer area.

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Section: Introductionmentioning

confidence: 99%

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

et al. 2014

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“…The LED device structures consisted of five GaInN/GaN QWs sandwiched between n-type GaN on the substrate and a ptype GaN layer grown by metal organic chemical vapor phase epitaxy [1,2]. In addition, a thin (~ 20 nm) AlGaN Micro-Raman spectroscopy was performed in z(x,.…”

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confidence: 99%

Junction temperature analysis in green light emitting diode dies on sapphire and GaN substrates

Senawiratne

Zhao

Detchprohm

et al. 2008

Phys. Status Solidi (c)

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We investigate pn‐junction heating in 525 nm green GaInN/GaN quantum well light emitting diode dies by micro‐Raman and photoluminescence spectroscopy. We compare dies grown on GaN and sapphire substrates of different sizes at current densities up to 267 A/cm2. Analysis of the experiments was supported by realistic three‐dimensional finite‐element simulations of the thermal properties. Sapphire based LED dies reach a junction temperature as high as 240 °C at a current density of 133 A/cm2, while those on bulk GaN only heat to 83 °C. This corresponds to a thermal resistance of 428 K/W and 63 K/W, respectively. By help of this calibration, the role of junction temperature in the spectral light output performance is identified. From the numerical simulation, dimensions and thermal conductivity of the substrate are identified as the dominant control parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Since the p-type GaN cannot fill in the gap entirely, pits with diameter from 300 nm to 500 nm remain at the surface, and can be observed in the scanning electron microscopy (SEM) images. 5 Thus the density of such large inverted pyramids was determined to be around 3 · 10 5 cm -2 by counting the pits in the SEM images. The TDs themselves continue to propagate until they reach the sample surface.…”

Section: Homoepitaxial Ledsmentioning

confidence: 99%

“…Recently, we demonstrated that the light output power from homoepitaxial LED dies can be more than one order of magnitude higher than that of heteroepitaxial dies. 5 In this study, we explore the material structure by transmission electron microscopy (TEM) for any cause of the performance differences.…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization of Homoepitaxial Blue GaInN/GaN Light-Emitting Diodes by Transmission Electron Microscopy

Zhu

Xia

Zhao

et al. 2008

Journal of Elec Materi

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We perform a transmission electron microscopy (TEM) characterization of blue light-emitting diode epiwafers grown homoepitaxially on a c-plane GaN substrate and compare with such grown on sapphire. We find a threading dislocation (TD) density as low as 2 · 10 8 cm -2 in homoepitaxial growth, which is 1/30 of that in sapphire-based material. A unique type of inverted pyramid defect with diameter $650 nm was observed. It originates from the homo-interface in edge-type TDs. TDs were also found to be generated within the quantum wells without a precursor TD defect. Otherwise, high-resolution TEM suggests extremely homogeneous quantum wells and barriers in terms of composition and well width. Besides plan-view TEM, wet chemical etching on n-type GaN was carried out in hot phosphoric acid to evaluate the TD density more quickly. The two methods prove to be equivalent with respect of determined TD densities.

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Dislocation analysis in homoepitaxial GaInN/GaN light emitting diode growth

Cited by 28 publications

References 9 publications

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

LEDs on HVPE grown GaN substrates: Influence of macroscopic surface features

Junction temperature analysis in green light emitting diode dies on sapphire and GaN substrates

Structural Characterization of Homoepitaxial Blue GaInN/GaN Light-Emitting Diodes by Transmission Electron Microscopy

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