Modulating lateral strain in GaN-based epitaxial layers by patterning sapphire substrates with aligned carbon nanotube films

Long, Haitao; Wei, Yang; Yu, Tongjun; Wang, Zhe; Jia, Chuanyu; Yang, Zhijian; Zhang, Guoyi; Fan, Shoushan

doi:10.1007/s12274-012-0250-1

Cited by 19 publications

(17 citation statements)

References 26 publications

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“…A TEM test was performed on the cross-sectional GaN sample to demonstrate the threading dislocation (TD) blocking mechanism of the CNT network. Figure 2a,b shows the bright-field cross-sectional TEM images under the twobeam diffraction conditions with g = [0002] and [11][12][13][14][15][16][17][18][19][20]. Consistent with our SEM test result, high-density nanovoids that are related to GaN coalescence around CNTs can be observed.…”

Section: ■ Results and Discussionsupporting

confidence: 77%

“…In this work, a network combining functions of dislocation prevention and thermal transport is proposed and established by carbon nanotubes (CNTs) on PSS and contributes significantly to both TDD reduction and heat dissipation improvement in an economical way. A second selective growth process, or more specifically, a dislocation blocking process, is successfully introduced on the basis of PSS by cross-stacked CNTs, which has been proven effective in epilayer TDD reduction at an initial nucleation stage − and subsequent device performance improvements . Meanwhile, the high axial thermal conductivity of CNTs enables this network to uniform the temperature distribution and increase the thermal transport efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Efficient Dislocation Prevention and Thermal Transport Network Constructed by CNT Films on PSS for GaN-Based UV LEDs

Wang

Tian

et al. 2021

ACS Appl. Electron. Mater.

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We report the realization of a dislocation prevention and thermal transport network by adopting carbon nanotube (CNT) films on a commercially available patterned sapphire substrate (PSS), using which a high-quality gallium nitride (GaN) epilayer and a device with improved thermal performance are achieved at the same time. High fill factor CNT films with easy accessibility are lifted above the sapphire patterns and introduce a second selective area growth subsequent to the micron-scale selective area growth on PSS, leading to a further reduction in threading dislocation density (TDD) without involving any regrowth process. Under this dislocation prevention effect, the TDD of the GaN epilayer dropped to 3.5 × 10 7 cm −2 consequently, which is 78% lower than that on PSS. A thermal transporting network of CNTs with high axial thermal conductivity is simultaneously established, contributing to the great improvement in the thermal performance of the near-ultraviolet light-emitting diode (LED) fabricated subsequently. As a result, an 89% increase in saturation light output power and a 55.5% enhancement in internal quantum efficiency were acquired. We thus believe that this convenient yet effective method will be a competitive solution for shortwavelength LED devices that require high efficiency and long lifetime.

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Section: ■ Results and Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Efficient Dislocation Prevention and Thermal Transport Network Constructed by CNT Films on PSS for GaN-Based UV LEDs

Wang

Tian

et al. 2021

ACS Appl. Electron. Mater.

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“…Previously, we proposed a carbon-nanotube-patterned sapphire substrate (CNPSS) 18) which has many advantages such as low cost, mass-producibility, and scalability. In previous reports, different lateral strain distributions and stress reductions were analyzed in a GaN film on a CNPSS, and the growth process of the CNPSS was optimized.…”

Section: Introductionmentioning

confidence: 99%

Effect of layers of carbon-nanotube-patterned substrate on GaN-based light-emitting diodes

Shan

Wei

Sun

et al. 2015

Jpn. J. Appl. Phys.

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In this paper, the high-performance GaN-based light-emitting diodes (LEDs) with coated carbon nanotubes (CNTs) on sapphire substrates, fabricated by metal-organic chemical vapor deposition (MOCVD), were demonstrated. The different layers of a CNT-patterned sapphire substrate (CNPSS) grown by an optimized growth process were discussed. Results of X-ray diffraction (XRD) showed the threading dislocations to be suppressed, thus the crystal quality of the GaN film was improved by introducing the carbon nanotube films. The LEDs with a CNPSS exhibited lower reverse-bias current and divergent angle, and larger enhancement of the light output power (LOP) compared with the conventional LEDs. With the increase in the number of layers of CNTs, the CNPSS-LED exhibited better crystal quality and photoelectric property, but more layers of CNTs also absorbed more light. There is a trade-off between the crystalline quality of the LED and light absorption.

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“…The concept of adding carbon nanotubes (CNTs) into conventionally non-conductive polymers to enhance their electrical properties has attracted significant attentions over the years [1][2][3][4]. One of the most amazing features of these smart materials is that their own strain can be measured by monitoring their electrical resistance variation.…”

Section: Introductionmentioning

confidence: 99%

Modeling sensor behavior of CNT/polymer nanocomposite

Gong

Zhu

2014

14th IEEE International Conference on Nanotechnology

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This work investigates the electric conductivity and sensor behavior of CNT/polymer nanocomposite using a 3-dimensional CNT percolating network model, where the CNTs are allowed to deform and bend at crossed junctions of nanotubes. The comparison of the numerical results and experimental data showed a reasonably good agreement. Monte Carlo simulation reveal that besides tunneling resistance, deformation-induced resistance also plays a significant role in both electrical conductivity and sensor behavior of CNT/polymer composites. In our physics-based model, working mechanisms for high sensitivity at low CNT loading and asymmetric sensor behavior between tensile and compress strains were discussed.978-1-4799-5622-7/$31.00 ©2014 IEEE

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Modulating lateral strain in GaN-based epitaxial layers by patterning sapphire substrates with aligned carbon nanotube films

Cited by 19 publications

References 26 publications

Efficient Dislocation Prevention and Thermal Transport Network Constructed by CNT Films on PSS for GaN-Based UV LEDs

Efficient Dislocation Prevention and Thermal Transport Network Constructed by CNT Films on PSS for GaN-Based UV LEDs

Effect of layers of carbon-nanotube-patterned substrate on GaN-based light-emitting diodes

Modeling sensor behavior of CNT/polymer nanocomposite

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