Crystallography and cathodoluminescence of pyramid-like GaN nanorods epitaxially grown on a sapphire substrate

Liu, Baodan; Wang, Zaien; Yuan, Fang; Dierre, Benjamin; Sekiguchi, Takashi; Jiang, Xin

doi:10.1039/c3ra44371j

Cited by 20 publications

(20 citation statements)

References 10 publications

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“…S4. † Unlike the smooth side surface of GaN nanorods, 36 the GaN nanowires synthesized in this work exhibit a corrugated appearance, which is composed of periodic concave and convex crystalline planes, as clearly observed in the SEM image and TEM image ( Fig. 2a-c).…”

Section: Resultsmentioning

confidence: 71%

“…It should be noted that the crystallization rates at the edge and center in the liquid-solid interface may be strongly dependent on the temperature fluctuation, gas flowing rate or local composition inhomogeneity, as validated by cathodoluminescence spectroscopy in GaN nanopyramids. 36 This assumption can be further supported by the GaN nanotubes prepared at a large NH 3 flowing rate. 48 Besides voids, stacking faults (SFs) featured as dark contrast stripes are clearly observed along the radial direction, two of which are marked by white arrows in Fig.…”

Section: Resultsmentioning

confidence: 78%

“…Over the past few years, our group has made considerable efforts toward the nucleation design, crystallographic alignment control, structural defect depression and cathodoluminescence study of GaN nanowires processed by CVD methods. [30][31][32][33] Though single-crystalline GaN nanowire arrays grown along specific crystallographic directions have been successfully obtained with or without the assistance of metal catalysts, the realization of homogeneous GaN nanowires with superior alignment on an industrially scalable substrate still remains a challenge. Particularly, with the enlargement of the substrate size, GaN nanowires with different orientations will appear and the alignment uniformity of GaN nanowires becomes poor, which will affect the integration of GaN-based nanodevices and performance stability.…”

Section: Introductionmentioning

confidence: 99%

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Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires

Liu

Yang

et al. 2017

Nanoscale

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Well-aligned GaN nanowires are promising candidates for building high-performance optoelectronic nanodevices. In this work, we demonstrate the epitaxial growth of well-aligned GaN nanowires on a [0001]-oriented sapphire substrate in a simple catalyst-assisted chemical vapor deposition process and their alignment control. It is found that the ammonia flux plays a key role in dominating the initial nucleation of GaN nanocrystals and their orientation. Typically, significant improvement of the GaN nanowire alignment can be realized at a low NH flow rate. X-ray diffraction and cross-sectional scanning electron microscopy studies further verified the preferential orientation of GaN nanowires along the [0001] direction. The growth mechanism of GaN nanowire arrays is also well studied based on cross-sectional high-resolution transmission electron microscopy (HRTEM) characterization and it is observed that GaN nanowires have good epitaxial growth on the sapphire substrate following the crystallographic relationship between (0001)∥(0001) and (101[combining macron]0)∥(112[combining macron]0). Most importantly, periodic misfit dislocations are also experimentally observed in the interface region due to the large lattice mismatch between the GaN nanowire and the sapphire substrate, and the formation of such dislocations will favor the release of structural strain in GaN nanowires. HRTEM analysis also finds the existence of "type I" stacking faults and voids inside the GaN nanowires. Optical investigation suggests that the GaN nanowire arrays have strong emission in the UV range, suggesting their crystalline nature and chemical purity. The achievement of aligned GaN nanowires will further promote the wide applications of GaN nanostructures toward diverse high-performance optoelectronic nanodevices including nano-LEDs, photovoltaic cells, photodetectors etc.

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires

Liu

Yang

et al. 2017

Nanoscale

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“…Wurtzite GaN film was grown on c-plane sapphire substrate by Hydrogen Vapor Phase Epitaxy (HVPE) method [23], GaN nanowires and nanoflowers grown on sapphire substrate were obtained through a simple chemical vapor deposition (CVD) process, as described in our previous work [24].…”

Section: Materials Synthesismentioning

confidence: 99%

Anodic stripping voltammetry of silver(I) using unmodified GaN film and nanostructure electrodes

Liu

Yuan

et al. 2015

Applied Surface Science

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“…As this process only produced a few crystals, it was evaluated with no market development at that time. Then, in 1969, Maruska and Tietjen (Maruska & Tietjen, ) used chemical vapour deposition to successfully grow a GaN film, of a large‐sized area, on a sapphire (Al 2 O 3 ) substrate, thus attracting more interested researchers (Liu et al, ) to do related studies. However, because the sapphire substrate is expensive, and its size is only 2 inches, the price of GaN‐based LEDs has always been high.…”

Section: Introductionmentioning

confidence: 99%

Differences in the nanoscale electrical properties of GaN films grown on sapphire and ZnO substrates by molecular beam epitaxy

Chen

Chang

et al. 2017

Microscopy Res & Technique

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Gallium nitride (GaN) films were grown on sapphire and zinc oxide (ZnO) single crystal substrates using plasma-assisted molecular beam epitaxy. As ZnO for GaN have a better lattice match, the coverage ratio of the GaN (002) plane on the ZnO substrate was significantly higher by about 45%. According to conducting atomic force microscopy and scanning surface potential microscopy measurements, the surface of GaN films grown on the ZnO substrate had two excellent physical characteristics: (a) an 18% reduction of the high contact current region, and (b) a highly uniform work function distribution. Therefore, for future applications in GaN-based light-emitting diodes, the use of ZnO as a substrate will prolong the luminescence lifetime and enhance the luminescent monochromaticity.

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Crystallography and cathodoluminescence of pyramid-like GaN nanorods epitaxially grown on a sapphire substrate

Cited by 20 publications

References 10 publications

Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires

Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires

Anodic stripping voltammetry of silver(I) using unmodified GaN film and nanostructure electrodes

Differences in the nanoscale electrical properties of GaN films grown on sapphire and ZnO substrates by molecular beam epitaxy

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