Growth study of self-assembled GaN nanocolumns on silica glass by plasma assisted molecular beam epitaxy

Mulyo, Andreas Liudi; Konno, Yuta; Nilsen, Julie Stene; Helvoort, Antonius T. J. van; Fimland, B. O.; Weman, H.; Kishino, Katsumi

doi:10.1016/j.jcrysgro.2017.10.009

Cited by 23 publications

(15 citation statements)

References 66 publications

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“…The exact number of layers cannot be confirmed by this image, as the graphene layers are buckled and the two-dimensional image of the TEM lamella thus indicates more than two layers . The nanocolumns exhibit a pure wurtzite crystal structure and no interfacial layer, which is identical with our observation in the growth of n-GaN nanocolumns on graphene using an MEE-AlN buffer layer but different from n-GaN nanocolumns grown directly on silica glass . No dislocations, stacking faults or other defects are found in the GaN- and AlGaN-nanocolumn segments.…”

Section: Nanocolumn Growth and Structural Characterizationsupporting

confidence: 74%

“…23 The nanocolumns exhibit a pure wurtzite crystal structure and no interfacial layer, which is identical with our observation in the growth of n-GaN nanocolumns on graphene using an MEE-AlN buffer layer 23 but different from n-GaN nanocolumns grown directly on silica glass. 41 No dislocations, stacking faults or other defects are found in the GaN-and AlGaNnanocolumn segments. The AlN buffer layer, however, is found to have some dislocations and point defects.…”

Section: Nano Lettersmentioning

confidence: 99%

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GaN/AlGaN Nanocolumn Ultraviolet Light-Emitting Diode Using Double-Layer Graphene as Substrate and Transparent Electrode

et al. 2019

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The many outstanding properties of graphene have impressed and intrigued scientists for the last few decades. Its transparency to light of all wavelengths combined with a low sheet resistance makes it a promising electrode material for novel optoelectronics. So far, no one has utilized graphene as both the substrate and transparent electrode of a functional optoelectronic device. Here, we demonstrate the use of double-layer graphene as a growth substrate and transparent conductive electrode for an ultraviolet light-emitting diode in a flip-chip configuration, where GaN/AlGaN nanocolumns are grown as the light emitting structure using plasma-assisted molecular beam epitaxy. Although the sheet resistance is increased after nanocolumn growth compared with pristine double-layer graphene, our experiments show that the double-layer graphene functions adequately as an electrode. The GaN/AlGaN nanocolumns are found to exhibit a high crystal quality with no observable defects or stacking faults. Room temperature electroluminescence measurements show a GaN related near bandgap emission peak at 365 nm and no defect-related yellow emission.

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Section: Nanocolumn Growth and Structural Characterizationsupporting

confidence: 74%

Section: Nano Lettersmentioning

confidence: 99%

GaN/AlGaN Nanocolumn Ultraviolet Light-Emitting Diode Using Double-Layer Graphene as Substrate and Transparent Electrode

et al. 2019

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“…Optical studies were done using RT micro-photoluminescence with a He-Cd laser (325 nm) as the excitation source. A freestanding HVPE-grown GaN bulk substrate (threading dislocation density of 6-8 × 10 6 cm −2 ) was used as the reference sample like for previous studies 21,24 .…”

Section: Methodsmentioning

confidence: 99%

The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene

Mulyo

Rajpalke

Vullum

et al. 2020

Sci Rep

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GaN nanocolumns were synthesized on single-layer graphene via radio-frequency plasma-assisted molecular beam epitaxy, using a thin migration-enhanced epitaxy (MEE) AlN buffer layer as nucleation sites. Due to the weak nucleation on graphene, instead of an AlN thin-film we observe two distinguished AlN formations which affect the subsequent GaN nanocolumn growth: (i) AlN islands and (ii) AlN nanostructures grown along line defects (grain boundaries or wrinkles) of graphene. Structure (i) leads to the formation of vertical GaN nanocolumns regardless of the number of AlN MEE cycles, whereas (ii) can result in random orientation of the nanocolumns depending on the AlN morphology. Additionally, there is a limited amount of direct GaN nucleation on graphene, which induces nonvertical GaN nanocolumn growth. The GaN nanocolumn samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffraction, room temperature micro-photoluminescence, and micro-Raman measurements. Surprisingly, the graphene with AlN buffer layer formed using less MEE cycles, thus resulting in lower AlN coverage, has a lower level of nitrogen plasma damage. The AlN buffer layer with lowest AlN coverage also provides the best result with respect to high-quality and vertically-aligned GaN nanocolumns. Recent progresses in the growth of GaN thin-film on graphene 1-6 increasingly justify the possibility for graphene to be a good alternative substrate over the available conventional substrates, for instance Si 7,8 , SiC 9 and sapphire 10. It is also reported that GaN thin-film is achievable on sapphire or amorphous substrates by employing either multi-layer or single-layer graphene as buffer layer 11-14. Such exploitations can be realized by taking advantage of the weak quasi-van der Waals binding 15-17 which can drastically relax the lattice matching condition to be satisfied by constituent materials. That being said, the lack of chemical reactivity of graphene and its extremely low surface energy 18 greatly disrupt the nucleation process of GaN, resulting in a low nucleation density 19 and difficulty in controlling the stacking sequence of the GaN growth 3. The latter issue, which often manifests in the form of stacking faults 3,5 or threading dislocations 1,4,17 , can possibly be suppressed by growing nanowire or nanocolumn structures 16,20-25. Nevertheless, because of the absence of dangling bonds in graphene, nanocolumns are often aligned in non-vertical directions 26-28 and/or have low density 27,29. Both problems are required to be addressed in order to demonstrate that the growth of III-N semiconductor nanostructures, particularly nanocolumns, utilizing graphene as the substrate can be further considered as an alternative platform in enabling the advancement of optoelectronic device performance and functionality, for instance light-emitting diodes 30. In this regard, the introduction of defects in graphene by means of plasma treatments could alleviate the issue of absence of dangling...

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“…Therefore, nanowire LEDs have been widely studied for their possible use in full-color displays [108][109][110][111]. Compared with conventional InGaN/GaN quantum-well LEDs, nanowire heterostructures have many obvious advantages, including greatly reducing the dislocation density and polarization field in the active region of the device, improving the light extraction efficiency, and offering good compatibility with low-cost, large-area silicon substrates [112][113][114][115]. Such nanostructures include dot-in-a-wire nanowires, core/shell nanowires, and nano-column structures.…”

Section: Monolithic Wavelength Tunable Nanowire Ledmentioning

confidence: 99%

Full-Color Realization of Micro-LED Displays

et al. 2020

Nanomaterials

150

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Emerging technologies, such as smart wearable devices, augmented reality (AR)/virtual reality (VR) displays, and naked-eye 3D projection, have gradually entered our lives, accompanied by an urgent market demand for high-end display technologies. Ultra-high-resolution displays, flexible displays, and transparent displays are all important types of future display technology, and traditional display technology cannot meet the relevant requirements. Micro-light-emitting diodes (micro-LEDs), which have the advantages of a high contrast, a short response time, a wide color gamut, low power consumption, and a long life, are expected to replace traditional liquid-crystal displays (LCD) and organic light-emitting diodes (OLED) screens and become the leaders in the next generation of display technology. However, there are two major obstacles to moving micro-LEDs from the laboratory to the commercial market. One is improving the yield rate and reducing the cost of the mass transfer of micro-LEDs, and the other is realizing a full-color display using micro-LED chips. This review will outline the three main methods for applying current micro-LED full-color displays, red, green, and blue (RGB) three-color micro-LED transfer technology, color conversion technology, and single-chip multi-color growth technology, to summarize present-day micro-LED full-color display technologies and help guide the follow-up research.

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Growth study of self-assembled GaN nanocolumns on silica glass by plasma assisted molecular beam epitaxy

Cited by 23 publications

References 66 publications

GaN/AlGaN Nanocolumn Ultraviolet Light-Emitting Diode Using Double-Layer Graphene as Substrate and Transparent Electrode

GaN/AlGaN Nanocolumn Ultraviolet Light-Emitting Diode Using Double-Layer Graphene as Substrate and Transparent Electrode

The influence of AlN buffer layer on the growth of self-assembled GaN nanocolumns on graphene

Full-Color Realization of Micro-LED Displays

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