Microstructural analysis of InGaN/GaN epitaxial layers of metal organic chemical vapor deposition on c-plane of convex patterned sapphire substrate

Wan, Zhixin; He, Yinsheng; Choi, Chel‐Jong; Suh, Eun‐Kyung; Yu, Young Moon; Yi, Sam-Nyung; Ahn, Hyung-Soo; Yang, Min; Lee, Hyojong; Shin, Keesam

doi:10.1016/j.tsf.2013.05.111

Cited by 4 publications

(4 citation statements)

References 17 publications

(20 reference statements)

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“…The skew dislocation density, and pure edge and mixed dislocation densities in as-grown GaN epi-layer are estimated to be 7.9 × 10 7 , and 8.8 × 10 7 cm −2 , respectively2728. This crystalline quality of GaN-based LEDs grown on LSAT substrates is much better than traditional GaN-based LEDs prepared on sapphire and nanopatterned sapphire substrates2930313233.…”

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confidence: 91%

“…Actually, there is a ~1.5 nm blue shift in PL peak conducted at LT when compared with that at RT. This is attributed to the fact that there are high-energy carriers existing at low temperature, which lead to the low wavelength during the radiative recombination293031323345. It is widely accepted that the IQE can be estimated as the ratio of the peak PL intensities I RT at RT and I LT at LT, where the LT IQE is assumed to be 100%46.…”

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confidence: 99%

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Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates

Wang

Yang

Gao

et al. 2015

Sci Rep

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Highly-efficient GaN-based light-emitting diode (LED) wafers have been grown on La0.3Sr1.7AlTaO6 (LSAT) substrates by radio-frequency molecular beam epitaxy (RF-MBE) with optimized growth conditions. The structural properties, surface morphologies, and optoelectronic properties of as-prepared GaN-based LED wafers on LSAT substrates have been characterized in detail. The characterizations have revealed that the full-width at half-maximums (FWHMs) for X-ray rocking curves of GaN(0002) and GaN(10-12) are 190.1 and 210.2 arcsec, respectively, indicating that high crystalline quality GaN films have been obtained. The scanning electron microscopy and atomic force microscopy measurements have shown the very smooth p-GaN surface with the surface root-mean-square (RMS) roughness of 1.3 nm. The measurements of low-temperature and room-temperature photoluminescence help to calculate the internal quantum efficiency of 79.0%. The as-grown GaN-based LED wafers have been made into LED chips with the size of 300 × 300 μm2 by the standard process. The forward voltage, the light output power and the external quantum efficiency for LED chips are 19.6 W, 2.78 V, and 40.2%, respectively, at a current of 20 mA. These results reveal the high optoelectronic properties of GaN-based LEDs on LSAT substrates. This work brings up a broad future application of GaN-based devices.

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confidence: 91%

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confidence: 99%

Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates

Wang

Yang

Gao

et al. 2015

Sci Rep

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“…Particularly, III-nitride based vertical devices, such as vertical-cavity surface-emitting lasers (VCSELs), are costly and challenging to produce, thus compromising on the efficiency obtained. For example, the efficiency of devices grown on Al 2 O 3 is threatened by the introduction of high threading dislocation density (TDD) 4 5 due to a large lattice mismatch (14%) and a large difference in thermal expansion coefficients between III-nitride semiconductor and the substrate 6 7 . This high TDD causes many nonradiative recombinations and scattering centers, which will deteriorate the optical and electrical quality of III-nitride devices 8 .…”

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confidence: 99%

High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

Muhammed

Roldán

Yamashita³

et al. 2016

Sci Rep

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We demonstrate the high structural and optical properties of InxGa1−xN epilayers (0 ≤ x ≤ 23) grown on conductive and transparent (01)-oriented β-Ga2O3 substrates using a low-temperature GaN buffer layer rather than AlN buffer layer, which enhances the quality and stability of the crystals compared to those grown on (100)-oriented β-Ga2O3. Raman maps show that the 2″ wafer is relaxed and uniform. Transmission electron microscopy (TEM) reveals that the dislocation density reduces considerably (~4.8 × 107 cm−2) at the grain centers. High-resolution TEM analysis demonstrates that most dislocations emerge at an angle with respect to the c-axis, whereas dislocations of the opposite phase form a loop and annihilate each other. The dislocation behavior is due to irregular (01) β-Ga2O3 surface at the interface and distorted buffer layer, followed by relaxed GaN epilayer. Photoluminescence results confirm high optical quality and time-resolved spectroscopy shows that the recombination is governed by bound excitons. We find that a low root-mean-square average (≤1.5 nm) of InxGa1−xN epilayers can be achieved with high optical quality of InxGa1−xN epilayers. We reveal that (01)-oriented β-Ga2O3 substrate has a strong potential for use in large-scale high-quality vertical light emitting device design.

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“…The widely used sapphire (Al 2 O 3 ) substrate has large lattice mismatch (14% with GaN) and large thermal expansion coefficient mismatch (30% with GaN) with III-Nitrides materials [30,31,32], which will introduce high threading dislocation density (TDD) [32,33] acting as nonradiative recombination and scattering centers that deteriorate the performance of LEDs [34]. Furthermore, LEDs are fabricated in a horizontal structure since the sapphire substrates are insulated, leading to that both the n- and p-contact must be established at the top surface of the devices.…”

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confidence: 99%

Epitaxy of III-Nitrides on β-Ga2O3 and Its Vertical Structure LEDs

Zhang

Rong

et al. 2019

Micromachines

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β-Ga2O3, characterized with high n-type conductivity, little lattice mismatch with III-Nitrides, high transparency (>80%) in blue, and UVA (400–320 nm) as well as UVB (320–280 nm) regions, has great potential as the substrate for vertical structure blue and especially ultra violet LEDs (light emitting diodes). Large efforts have been made to improve the quality of III-Nitrides epilayers on β-Ga2O3. Furthermore, the fabrication of vertical blue LEDs has been preliminarily realized with the best result that output power reaches to 4.82 W (under a current of 10 A) and internal quantum efficiency (IQE) exceeds 78% by different groups, respectively, while there is nearly no demonstration of UV-LEDs on β-Ga2O3. In this review, with the perspective from materials to devices, we first describe the basic properties, growth method, as well as doping of β-Ga2O3, then introduce in detail the progress in growth of GaN on (1 0 0) and (−2 0 1) β-Ga2O3, followed by the epitaxy of AlGaN on gallium oxide. Finally, the advances in fabrication and performance of vertical structure LED (VLED) are presented.

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Microstructural analysis of InGaN/GaN epitaxial layers of metal organic chemical vapor deposition on c-plane of convex patterned sapphire substrate

Cited by 4 publications

References 17 publications

Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates

Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates

High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

Epitaxy of III-Nitrides on β-Ga2O3 and Its Vertical Structure LEDs

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