Self-organized propagation of dislocations in GaN films during epitaxial lateral overgrowth

Sakai, Akira; Sunakawa, Hajime; Kimura, Akitaka; Usui, Akira

doi:10.1063/1.125781

Cited by 61 publications

(30 citation statements)

References 12 publications

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“…Several techniques were developed in the 1990s to improve the quality of GaN films and devices, one of which was the application of lateral epitaxial overgrowth (LEO) to reduce dislocation density. LEO has been demonstrated to be an effective approach for the reduction of extended defect density in c-plane GaN by both MOCVD [47][48][49][50] and HVPE [51][52][53][54].…”

Section: Defect Reduction In Nonpolar Ganmentioning

confidence: 99%

Progress in the growth of nonpolar gallium nitride

Haskell

Nakamura

DenBaars

et al. 2007

Physica Status Solidi (b)

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The active regions of conventional c-plane (Al,In,Ga)N optoelectronic devices suffer from deleterious polarization effects. These polarization effects can be eliminated by growing devices on alternative GaN planes, such as {1 100} m-plane or {1120} a-plane films. Previous attempts to grow nonpolar GaN by vapor phase and molecular beam epitaxy methods yielded rough and faceted surfaces that were unsuitable for device use. Beginning with Waltereit et al.'s work [Nature, 406, 865 (2000)], significant progress has been made in improving nonpolar GaN structural quality and morphology. This paper reviews the structural and morphological characteristics of planar, nonpolar a-plane and m-plane GaN films grown by vapor phase and molecular beam epitaxy techniques. Defect reduction via lateral epitaxial overgrowth, and the influence of extended defects on surface morphology will be further discussed.

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Section: Defect Reduction In Nonpolar Ganmentioning

confidence: 99%

Progress in the growth of nonpolar gallium nitride

Haskell

Nakamura

DenBaars

et al. 2007

Physica Status Solidi (b)

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“…As was seen in the earliest cantilever epitaxy work and in Facet Controlled ELO (FACELO) research [9,16,17] VTDs turn and run horizontally when they encounter a free faceted face. This can be seen in ELO pyramids and near the edges of large cantilever posts.…”

Section: Nucleation Layer and Growth Of The Gablementioning

confidence: 99%

Defect reduction in gallium nitride using cantilever epitaxy.

Mitchell¹

2003

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Cantilever epitaxy (CE) has been developed to produce GaN on sapphire with low dislocation densities as needed for improved devices. The basic mechanism of seeding growth on sapphire mesas and lateral growth of cantilevers until they coalesce has been modified with an initial growth step at 950°C. This step produces a gable with ) 2 2 11 ( facets over the mesas, which turns threading dislocations from vertical to horizontal in order to reduce the local density above mesas. This technique has produced material with densities as low as 2-3x10 7 /cm 2 averaged across extended areas of GaN on sapphire, as determined with AFM, TEM and cathodoluminescence (CL). This density is about two orders of magnitude below that of conventional planar growths; these improvements suggest that locating wide-area devices across both cantilever and mesa regions is possible. However, the first implementation of this technique also produced a new defect: cracks at cantilever coalescences with associated arrays of lateral dislocations. These defects have been labeled "dark-block defects" because they are non-radiative and appear as dark rectangles in CL images. Material has been grown that does not have dark-block defects. Examination of the evolution of the cantilever films for many growths, both partial and complete, indicates that producing a film without these defects requires careful control of growth conditions and crystal morphology at multiple steps. Their elimination enhances optical emission and uniformity over large (mm) size areas. ACKNOWLEDGMENTS

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“…Various advanced techniques, such as FIELO [12], FACE-LO [13], Pendeo-Epitaxy [14] and mass transport techniques [15], were contrived to obtain lowdislocation-density GaN crystal. Complicated microstructures, such as wing tilting, 901 bending of TDs, and generation of horizontal dislocations (HDs) have been reported in the GaN layers by the above techniques [16,17]. Most recently, two-step planar LEO has been reported to successfully lower the dislocation density to the 10 7 cm À2 ranges in the lateral epitaxy area [18].…”

Section: Introductionmentioning

confidence: 99%