Identifying threading dislocation types in ammonothermally grown bulk α-GaN by confocal Raman 3-D imaging of volumetric stress distribution

Joonas Holmi; Bakhysh H. Bairamov; Sami Suihkonen; Harri Lipsanen

doi:10.1016/j.jcrysgro.2018.07.024

Identifying threading dislocation types in ammonothermally grown bulk α-GaN by confocal Raman 3-D imaging of volumetric stress distribution

Joonas Holmi, Bakhysh H. Bairamov, Sami Suihkonen, Harri Lipsanen

Not published at VTT

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Abstract

This study demonstrates all-optical Raman scattering study of dislocations in ammonothermally grown α-GaN crystal and identifies an edge a-type threading dislocation (TD) using a confocal Raman 3-D imaging technique. These findings make possible the characterization of volumetric stress field and low TD density distributions over a large area on bulk α-GaN single crystal. The dislocation type effects on Raman shift are also discussed in detail (in order to identify the edge a-type and mixed a+c-type TDs, and theorize the invisibility of the screw c-type TDs). Authors are not aware of any previous reports using the confocal Raman 3-D imaging to identify the edge a-type and mixed a+c-type TDs.

Original language	English
Pages (from-to)	47-54
Number of pages	8
Journal	Journal of Crystal Growth
Volume	499
DOIs	https://doi.org/10.1016/j.jcrysgro.2018.07.024
Publication status	Published - 25 Jul 2018
MoE publication type	A1 Journal article-refereed

Funding

J. T. Holmi wishes to express his great gratitude to Dr. Nagarajan Subramaniyam for excellent discussions and coaching. This work was financially supported primarily by the Academy of Finland (Grant 297916 ) and secondarily by Graphene Flagship GrapheneCore1 ( 696656 ). The research was performed at the OtaNano — Micronova Nanofabrication Centre of Aalto University.

Keywords

00-01
99-00
A1. Confocal Raman spectroscopy
A1. Dislocation types
A1. Stress distribution
A1. Three-dimensional (3-D) imaging
A2. Ammonothermal crystal growth
B1. Bulk hexagonal GaN

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title = "Identifying threading dislocation types in ammonothermally grown bulk α-GaN by confocal Raman 3-D imaging of volumetric stress distribution",

abstract = "This study demonstrates all-optical Raman scattering study of dislocations in ammonothermally grown α-GaN crystal and identifies an edge a-type threading dislocation (TD) using a confocal Raman 3-D imaging technique. These findings make possible the characterization of volumetric stress field and low TD density distributions over a large area on bulk α-GaN single crystal. The dislocation type effects on Raman shift are also discussed in detail (in order to identify the edge a-type and mixed a+c-type TDs, and theorize the invisibility of the screw c-type TDs). Authors are not aware of any previous reports using the confocal Raman 3-D imaging to identify the edge a-type and mixed a+c-type TDs.",

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AU - Bairamov, Bakhysh H.

AU - Suihkonen, Sami

AU - Lipsanen, Harri

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KW - A1. Dislocation types

KW - A1. Stress distribution

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JO - Journal of Crystal Growth

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ER -

Identifying threading dislocation types in ammonothermally grown bulk α-GaN by confocal Raman 3-D imaging of volumetric stress distribution

Abstract

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Keywords

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