Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry

Metzger, T. H.; Höpler, R.; Born, E.; Ambacher, O.; Stutzmann, M.; Stömmer, R.; Schuster, M.; Göbel, H.; Christiansen, Silke; Albrecht, M.; Strunk, H. P.

doi:10.1080/01418619808221225

Cited by 537 publications

(356 citation statements)

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“…Several extrapolation methods have been reported in the literature for the mean twist angle calculation [18,23,26]. However, all of these methods include a complicated calculation and fitting procedure for the extraction of the twist angle from the experimental data.…”

Section: Resultsmentioning

confidence: 99%

“…The outof-plane rotation of the blocks perpendicular to the surface normal is the mosaic tilt, and the in-plane rotation around the surface normal is the mosaic twist. The average absolute values of tilt and twist are directly related to the full width at half maximum (FWHM) of the corresponding distributions of the crystallographic orientations [18,23].…”

Section: Resultsmentioning

confidence: 99%

“…The influence of the nitridation time on the structural properties of a GaN epilayer Heteroepitaxial thin films with a large lattice-mismatch with respect to the substrate in turn form a mosaic structure of slightly misoriented sub-grains [18,19,22], which is characterized by the nucleation of slightly misoriented islands and the coalescence of these islands towards a smooth surface. The mosaic structure of the epilayers is determined by the size and angular distribution of the mosaic blocks.…”

Section: Resultsmentioning

confidence: 99%

“…Each contribution to the broadening of the particular XRD curves can be separated in the Williamson-Hall measurement [18,25]. Specifically, in triple-axis diffractometer measurements, the broadening of the rocking curve (angular-scan or ω-scan) of the symmetric (0002), (0004), and (0006) reflections for the GaN epitaxial layer is influenced only by the tilt angle α tilt and short coherence length parallel to the substrate surface L .…”

Section: Resultsmentioning

confidence: 99%

“…Large lattice mismatch with respect to the substrate commonly causes high dislocation densities in heteroepitaxial thin films [18][19][20][21]. These types of structures are often described by the model of mosaic crystals [20,22].…”

Section: Introductionmentioning

confidence: 99%

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The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

et al. 2008

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In the present paper, the effect of in-situ substrate nitridation time on crystalline quality of GaN films grown on Si (111) substrates by metal organic chemical vapor deposition (MOCVD) were investigated. A thin buffer layer of silicon nitride (SiN x ) with various thicknesses was achieved through the nitridation of substrate at different nitiridation times ranging from 0 to 660 s. The structural characteristics, such as dislocation densities, correlation lengths of columnar crystallites, the tilt and twist of the mosaic structure, and the angles of rotational disorder, were all studied in detail by using a planar and cross-sectional view of high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (HRXRD) performed at different scattering geometries. It was found that the dislocation densities, lateral coherence lengths, vertical coherence lengths, and the tilt and

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

et al. 2008

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Analysis of the Defect Structure of Epitaxial GaN

Heinke¹,

Kirchner

Einfeldt

et al. 1999

phys. stat. sol. (a)

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Mosaicity of GaN Epitaxial Layers: Simulation and Experiment

Chierchia

Böttcher

Figge

et al. 2001

phys. stat. sol. (b)

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High-resolution X-ray diffraction has been used to analyze GaN epilayers with varying coalescence thickness which were grown by MOVPE on (0001) oriented sapphire. The decrease of the density of edge type threading dislocations with increasing coalescence thickness causes a marked difference in the mosaicity of the samples. As the defects form along the grain boundaries, this corresponds to an increase in lateral coherence length with increasing coalescence thickness. The lateral coherence length has been obtained from simulations of reciprocal lattice points of off-axis Bragg reflections, measured in asymmetric diffraction geometry.Introduction The grain coalescence process during metal organic vapour phase epitaxy (MOVPE) of GaN on sapphire strongly influences the density of edge type threading dislocations (named edge dislocation density in the following). GaN is commonly grown utilizing a low temperature nucleation layer. During the successive high temperature growth three-dimensional islands form which coalesce towards a smooth film. This causes a reduction of the edge dislocation density with increasing coalescence thickness as the edge dislocations form along the crystallite boundaries to compensate for the inplane rotation (twist) of the islands [1-3]. The mosaic structure of the GaN layer is determined by a set of four parameters wich are illustrated in Fig. 1.The angular mismatch of the crystallites is given by the tilt and the twist, describing the angular distribution of the crystallographic orientation of the mosaic blocks perpendicular to and within the growth plane. The lateral and vertical dimensions of the crystallites are given by the lateral and vertical coherence length. All parameters can be accessed by X-ray diffraction. This work investigates the effect of tilt and lateral coherence length of the crystallites on the distribution of scattered intensity in reciprocal space. This will be discussed for the example of epitaxial layers grown with different coalescence thickness.

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Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry

Cited by 537 publications

References 20 publications

The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

Analysis of the Defect Structure of Epitaxial GaN

Mosaicity of GaN Epitaxial Layers: Simulation and Experiment

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