Analysis of the mosaic structure of an ordered (Al,Ga)N layer

Kirste, Lutz; Pavlov, Konstantin Mikhailovitch; Mudie, Stephen; Пунегов, В. И.; Herres, N.

doi:10.1107/s0021889804030675

Cited by 37 publications

(23 citation statements)

References 31 publications

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“…2,3 It has recently been shown that III-nitride layers grown on an Al 2 O 3 ͑0001͒ substrate have a predominantly mosaic structure consisting of c-oriented nanocolumns. 4,5 Furthermore the size dependence of Young's modulus has been revealed in nanocolumn structures, such as ZnO nanowires with a diameter of Ͻ120 nm ͑Ref. 6͒ or GaN nanotubes.…”

Section: Introductionmentioning

confidence: 99%

Internal strains and crystal structure of the layers in AlGaN/GaN heterostructures grown on a sapphire substrate

Kladko

Kolomys

Slobodian

et al. 2009

Journal of Applied Physics

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In this paper, we investigate the structural properties of AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition on sapphire substrates with different thicknesses using high-resolution x-ray diffraction and Raman scattering methods. We discuss the microscopic nature of spatial-inhomogeneous deformations and dislocation density in the structures. Microdeformations within mosaic blocks and the sizes of regions of coherent diffraction are determined. We reveal a gradient depth distribution of deformations in the mosaic structure of nitride layers, as well as at the interface regions of the sapphire substrate on the microscale level using confocal micro-Raman spectroscopy. We determine that an increase in substrate thickness leads to a reduction in dislocation density in the layers and an increase in the elastic deformations. The features of the block structure of nitrides layers are shown to have a significant influence on their elastic properties.

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Section: Introductionmentioning

confidence: 99%

Internal strains and crystal structure of the layers in AlGaN/GaN heterostructures grown on a sapphire substrate

Kladko

Kolomys

Slobodian

et al. 2009

Journal of Applied Physics

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“…It is important to note here that the diffraction peaks are not Gaussian in shape. However, as was shown in the experimental and theoretical investigations performed in recent years [5,6,17,18], they are approximated in the central part by the Voigt function with a certain fraction of the Lorentzian contribution, and the intensity on the wings of the peaks decreases more rapidly and, in the majority of the cases, as a power function. In this case, the law of decay in the intensity on the wings and the fraction of the Lorentzian broadening depend on the character of the distribution of the dislocations.…”

Section: Resultsmentioning

confidence: 91%

On the role of secondary extinction in the measurement of the integrated intensity of X-ray diffraction peaks and in the determination of the thickness of damaged epitaxial layers

Kyutt

2016

Phys. Solid State

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The integrated intensity of X-ray diffraction reflections has been measured for a series of epitaxial layers of AIII nitrides (GaN, AlN, AlGaN) grown on different substrates (sapphire, SiC) and characterized by different degrees of structural perfection. It has been shown that, despite a high density of dislocations and a significant broadening of the diffraction peaks, the obtained values are not described by the kinematic theory of X-ray diffraction and suggest the existence of extinction. The results have been analyzed on the basis of the Darwin and Zachariasen extinction models. The secondary extinction coefficients and the thicknesses of epitaxial layers have been determined using two orders of reflection both in the Bragg geometry (0002 and 0004) and in the Laue geometry ( ) and). It has been demonstrated that the secondary extinction coefficient is the greater, the smaller is the broadening of the diffraction peaks and, consequently, the dislocation density. It has been found that, for epitaxial layers with a regular system of threading dislocations, the secondary extinction coefficient for the Laue reflections is substantially greater than that for the Bragg reflections.

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“…XRD APD detection has also been applied in thin films for AlGaN on sapphire [8], GaAs on Si [9] and GaP on Si [10]. The idea is that weak ''antiphase'' reflections (APR) act as APD sensors.…”

Section: Introductionmentioning

confidence: 99%