Direct imaging of local strain relaxation along the side facets and the edges of hexagonal GaN pyramids by cathodoluminescence microscopy

Bertram, F.; Christen, J.; Schmidt, Michael; Hiramatsu, Kazumasa; Kitamura, Shota; Sawaki, Nobuhiko

doi:10.1016/s1386-9477(98)00114-3

Cited by 16 publications

(9 citation statements)

References 7 publications

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“…Here we find a gathering of nonradiative recombination centers, which are most likely caused by screw dislocations or bundles of them running in c-direction in the center of hexagonal columns. In fact, the presence of dislocations in the center of hexagonal structures has already been observed in comparable GaN samples [10][11][12].…”

Section: Article In Pressmentioning

confidence: 65%

Microscopic spatial distribution of bound excitons in high-quality ZnO

Bertram

Förster

Christen

et al. 2004

Journal of Crystal Growth

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Section: Article In Pressmentioning

confidence: 65%

Microscopic spatial distribution of bound excitons in high-quality ZnO

Bertram

Förster

Christen

et al. 2004

Journal of Crystal Growth

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“…3(b). 11,12 In complete contrast, the monochromatic image of I 0 / I 1 [ Fig. 3(c)] visualizing the local quantum efficiency for I 8 is very homogeneous and barely correlates with the morphology.…”

Section: Direct Evidence For Selective Impurity Incorporation At the mentioning

confidence: 99%

Direct evidence for selective impurity incorporation at the crystal domain boundaries in epitaxial ZnO layers

Bertram

Förster

Christen

et al. 2004

Applied Physics Letters

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A direct correlation of structural properties with the spatial distribution of bound exciton luminescence in ZnO epitaxial layers has been achieved on a microscopic scale using highly spatially and spectrally resolved cathodoluminescence. The morphology of the high quality ZnO layer is characterized by a distinct domain structure. While the laterally integrated cathodoluminescence spectrum shows narrow (full width at half maximum <3meV) I8 luminescence, a pronounced emission line at I0∕I1 emerges in the local spectra taken at domain boundaries. In complete contrast, no I0∕I1 emission is found inside the domains. Monochromatic images further evidence the selective incorporation of impurities at the grain boundaries of domains. Micro mappings of the I8 peak wavelength directly visualize the strain relaxation across the domains toward their very center, where a drop in quantum efficiency indicates enhanced defect concentration.

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“…Relaxation of compressive strain with increasing growth thickness may be expected to contribute to the observed redshift in such structures, 10 but such an effect would not be expected to persist to the apex (a height of ϳ8 m). The effect is however consistent with temperature gradients during QW growth: The InN fraction x in In x Ga 1−x N increases strongly with decreasing growth temperature, resulting in more indium being incorporated at the topographic extremes where radiative thermal losses are higher.…”

mentioning

confidence: 99%

Quantum dot emission from site-controlled InGaN∕GaN micropyramid arrays

Edwards

Martin

Watson

et al. 2004

Applied Physics Letters

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In x Ga 1 − x N quantum dots have been fabricated by the selective growth of GaN micropyramid arrays topped with InGaN∕GaN quantum wells. The spatially, spectrally, and time-resolved emission properties of these structures were measured using cathodoluminescence hyperspectral imaging and low-temperature microphotoluminescence spectroscopy. The presence of InGaN quantum dots was confirmed directly by the observation of sharp peaks in the emission spectrum at the pyramid apices. These luminescence peaks exhibit decay lifetimes of approximately 0.5ns, with linewidths down to 650μeV (limited by the spectrometer resolution).

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Direct imaging of local strain relaxation along the side facets and the edges of hexagonal GaN pyramids by cathodoluminescence microscopy

Cited by 16 publications

References 7 publications

Microscopic spatial distribution of bound excitons in high-quality ZnO

Microscopic spatial distribution of bound excitons in high-quality ZnO

Direct evidence for selective impurity incorporation at the crystal domain boundaries in epitaxial ZnO layers

Quantum dot emission from site-controlled InGaN∕GaN micropyramid arrays

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