Influence of an in situ-deposited intermediate layer inside GaN and AlGaN layers on SiC substrates

Engl, Karl; Beer, M.; Gmeinwieser, Nikolaus; Schwarz, Uli; Zweck, Josef; Wegscheider, Werner; Miller, S.; Miler, A.; Lugauer, H.‐J.; Brüderl, G.; Lell, A.; Härle, V.

doi:10.1016/j.jcrysgro.2005.10.115

Cited by 30 publications

(19 citation statements)

References 26 publications

(26 reference statements)

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“…As the threading dislocation (TD) density can be significant in GaN and especially in AlGaN grown heteroepitaxially on sapphire, all samples contained a SiN x micromask in the buffer layer to reduce the TD density [47][48][49]. The SiN x micromask was located about 300 nm away from the interface between the substrate and buffer layer in case of the samples containing a GaN buffer, and about 600 nm for the samples with an AlGaN buffer layer.…”

Section: Discussionmentioning

confidence: 99%

Microstructural and compositional analyses of GaN‐based nanostructures

Pretorius

Schmidt

Aschenbrenner

et al. 2011

Physica Status Solidi (b)

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Composition and microstructure of GaN-based island structures and distributed Bragg reflectors (DBRs) were investigated with transmission electron microscopy (TEM). We analysed free-standing InGaN islands and islands capped with GaN. Growth of the islands performed by molecular beam epitaxy (MBE) and metal organic vapour phase epitaxy (MOVPE) resulted in different microstructures. The islands grown by MBE were plastically relaxed. Cap layer deposition resulted in a rapid dissolution of the islands already at early stages of cap layer growth. These findings are confirmed by grazingincidence X-ray diffraction (GIXRD). In contrast, the islands grown by MOVPE relax only elastically.Strain state analysis (SSA) revealed that the indium concentration increases towards the tips of the islands. For an application as quantum dots, the islands must be embedded into DBRs. Structure and composition of Al y Ga 1-y N/GaN Bragg reflectors on top of an AlGaN buffer layer and In x Al 1-x N/ GaN Bragg reflectors on top of a GaN buffer layer were investigated. Specifically, structural defects such as threading dislocations (TDs) and inversion domains (IDs) were studied, and we investigated thicknesses, interfaces and interface roughnesses of the layers. As the peak reflectivities of the investigated DBRs do not reach the theoretical predictions, possible reasons are discussed.

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Section: Discussionmentioning

confidence: 99%

Microstructural and compositional analyses of GaN‐based nanostructures

Pretorius

Schmidt

Aschenbrenner

et al. 2011

Physica Status Solidi (b)

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“…Such crystal imperfections are known to affect the electrical and optical properties of GaN-based devices negatively, as they act as centers of nonradiative carrier recombination [1][2][3] and lead to degradation of LDs [4]. The in situ deposition of SiN x , acting as a nano-mask and influencing the morphology of the overgrown GaN layer, was found to be a fast and simple method leading to a defect reduction [5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Process optimization for the effective reduction of threading dislocations in MOVPE grown GaN using in situ deposited masks

Hertkorn

Lipski

Brückner

et al. 2008

Journal of Crystal Growth

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“…The latter can be deposited in-situ during the growth. However, Engl et al [5] could not observe any visible improvement in the crystal quality of Al 0.07 Ga 0.93 N epilayers due to the SiN x nanomask. It seems that the use of SiN x interlayers for the improvement of AlGaN epilayers is a challenging issue.…”

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In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN

Forghani

Gharavipour

Klein

et al. 2011

Phys. Status Solidi C

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We report the growth of high crystal quality Al0.3Ga0.7N directly on sapphire substrates with metalorganic vapour phase epitaxy. We studied the improvements in crystal quality by introducing an in‐situ deposited SiNx interlayer. It acts as a nanomask which results in termination of the dislocations near the interface between the nanomask and epilayer. The epilayers with no SiNx interlayer have very low density of screw type dislocations evident from transmission electron microscopy (TEM) investigations confirmed by a very narrow X‐ray diffraction symmetric reflection (60”). This is a result of our oxygen doped AlN nucleation layer used to grow such epilayers. On the other hand, such epilayers have very broad XRD asymmetric reflections (typically a few thousand arcsec) indicating a high density of edge type dislocations. We could decrease the latter which are the main existing dislocations in our AlGaN epilayers. In TEM micrographs, we observed the formation of dislocation “bundles” when introducing SiNx interlayers. This phenomenon promotes the dislocation free areas on the surface of the wafer. We carried out accurate optimizations of the SiNx deposition. Consequently, we could grow high quality Al0.3Ga0.7N epilayers with much narrower XRD asymmetric peaks–782” with total sample thickness of 1.4 µm (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Influence of an in situ-deposited intermediate layer inside GaN and AlGaN layers on SiC substrates

Cited by 30 publications

References 26 publications

Microstructural and compositional analyses of GaN‐based nanostructures

Microstructural and compositional analyses of GaN‐based nanostructures

Process optimization for the effective reduction of threading dislocations in MOVPE grown GaN using in situ deposited masks

In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN

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Influence of an in situ-deposited intermediate layer inside GaN and AlGaN layers on SiC substrates

Cited by 30 publications

References 26 publications

Microstructural and compositional analyses of GaN‐based nanostructures

Microstructural and compositional analyses of GaN‐based nanostructures

Process optimization for the effective reduction of threading dislocations in MOVPE grown GaN using in situ deposited masks

In‐situ deposited SiNx nanomask for crystal quality improvement in AlGaN

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In‐situ deposited SiN_x nanomask for crystal quality improvement in AlGaN