Reduction of threading dislocation density in Al0.12Ga0.88N epilayers by a multistep technique

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Reduction of threading dislocation density in Al0.12Ga0.88N epilayers by a multistep technique. / Lang, T.; Odnoblyudov, M. A.; Bougrov, V. E.; Suihkonen, S.; Svensk, O.; Törmä, P. T.; Sopanen, M.; Lipsanen, H.

In: Journal of Crystal Growth, Vol. 298, 01.2007, p. 276-280.

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Lang, T. ; Odnoblyudov, M. A. ; Bougrov, V. E. ; Suihkonen, S. ; Svensk, O. ; Törmä, P. T. ; Sopanen, M. ; Lipsanen, H. / Reduction of threading dislocation density in Al0.12Ga0.88N epilayers by a multistep technique. In: Journal of Crystal Growth. 2007 ; Vol. 298. pp. 276-280.

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@article{b54d2068bb7643689aa84e1c0a760424,
title = "Reduction of threading dislocation density in Al0.12Ga0.88N epilayers by a multistep technique",
abstract = "Although suitable for the reduction of the threading dislocation density in GaN layers the widely used two-step MOCVD method does not work as efficiently for AlGaN. This is due to slow surface diffusion of the Al species. In the present paper, the previously reported in situ multistep method for MOCVD growth of high-quality GaN films is adopted for the growth of Al0.12Ga0.88N films on c-plane sapphire. The developed method for AlGaN growth is virtually GaN free in the sense that no continuous film of GaN is needed near the substrate interface. Crack-free layers of Al0.12Ga0.88N with a thickness of about 2 μm are grown by the method. A sparse distribution of 3D GaN nucleation islands and stimulation of threading dislocation reactions enable a reduction of the threading dislocation density down to 5×108 cm-2 in the Al0.12Ga0.88N films. The threading dislocation density is evaluated by etch-pit density measurements. High-resolution X-ray diffraction and transmission electron microscopy are used to study the crystallinity of the Al0.12Ga0.88N layers. Reflectometry is utilized to analyze film growth in situ. The surface morphology of GaN nucleation layers and Al0.12Ga0.88N epilayers is characterized by atomic force microscopy.",
keywords = "A1. Nucleation, A1. Threading dislocations, A3. MOCVD, B1. AlGaN",
author = "T. Lang and Odnoblyudov, {M. A.} and Bougrov, {V. E.} and S. Suihkonen and O. Svensk and T{\"o}rm{\"a}, {P. T.} and M. Sopanen and H. Lipsanen",
year = "2007",
month = "1",
doi = "10.1016/j.jcrysgro.2006.10.088",
language = "English",
volume = "298",
pages = "276--280",
journal = "Journal of Crystal Growth",
issn = "0022-0248",
publisher = "Elsevier",

}

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TY - JOUR

T1 - Reduction of threading dislocation density in Al0.12Ga0.88N epilayers by a multistep technique

AU - Lang, T.

AU - Odnoblyudov, M. A.

AU - Bougrov, V. E.

AU - Suihkonen, S.

AU - Svensk, O.

AU - Törmä, P. T.

AU - Sopanen, M.

AU - Lipsanen, H.

PY - 2007/1

Y1 - 2007/1

N2 - Although suitable for the reduction of the threading dislocation density in GaN layers the widely used two-step MOCVD method does not work as efficiently for AlGaN. This is due to slow surface diffusion of the Al species. In the present paper, the previously reported in situ multistep method for MOCVD growth of high-quality GaN films is adopted for the growth of Al0.12Ga0.88N films on c-plane sapphire. The developed method for AlGaN growth is virtually GaN free in the sense that no continuous film of GaN is needed near the substrate interface. Crack-free layers of Al0.12Ga0.88N with a thickness of about 2 μm are grown by the method. A sparse distribution of 3D GaN nucleation islands and stimulation of threading dislocation reactions enable a reduction of the threading dislocation density down to 5×108 cm-2 in the Al0.12Ga0.88N films. The threading dislocation density is evaluated by etch-pit density measurements. High-resolution X-ray diffraction and transmission electron microscopy are used to study the crystallinity of the Al0.12Ga0.88N layers. Reflectometry is utilized to analyze film growth in situ. The surface morphology of GaN nucleation layers and Al0.12Ga0.88N epilayers is characterized by atomic force microscopy.

AB - Although suitable for the reduction of the threading dislocation density in GaN layers the widely used two-step MOCVD method does not work as efficiently for AlGaN. This is due to slow surface diffusion of the Al species. In the present paper, the previously reported in situ multistep method for MOCVD growth of high-quality GaN films is adopted for the growth of Al0.12Ga0.88N films on c-plane sapphire. The developed method for AlGaN growth is virtually GaN free in the sense that no continuous film of GaN is needed near the substrate interface. Crack-free layers of Al0.12Ga0.88N with a thickness of about 2 μm are grown by the method. A sparse distribution of 3D GaN nucleation islands and stimulation of threading dislocation reactions enable a reduction of the threading dislocation density down to 5×108 cm-2 in the Al0.12Ga0.88N films. The threading dislocation density is evaluated by etch-pit density measurements. High-resolution X-ray diffraction and transmission electron microscopy are used to study the crystallinity of the Al0.12Ga0.88N layers. Reflectometry is utilized to analyze film growth in situ. The surface morphology of GaN nucleation layers and Al0.12Ga0.88N epilayers is characterized by atomic force microscopy.

KW - A1. Nucleation

KW - A1. Threading dislocations

KW - A3. MOCVD

KW - B1. AlGaN

UR - http://www.scopus.com/inward/record.url?scp=33846404513&partnerID=8YFLogxK

U2 - 10.1016/j.jcrysgro.2006.10.088

DO - 10.1016/j.jcrysgro.2006.10.088

M3 - Article

VL - 298

SP - 276

EP - 280

JO - Journal of Crystal Growth

JF - Journal of Crystal Growth

SN - 0022-0248

ER -

ID: 4220047