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Incorporation and effects of impurities in different growth zones within basic ammonothermal GaN

Sintonen, Sakari; Kivisaari, Pyry LU ; Pimputkar, Siddha; Suihkonen, Sami; Schulz, Tobias; Speck, James S. and Nakamura, Shuji (2016) In Journal of Crystal Growth 456. p.43-50
Abstract

The ammonothermal method is one of the most promising candidates for large-scale bulk GaN growth due to its scalability and high crystalline quality. However, emphasis needs to be put on understanding the incorporation and effects of impurities during growth. This article discusses how impurities are incorporated in different growth zones in basic ammonothermal GaN, and how they affect the structural, electrical and optical properties of the grown crystal. The influence of growth time on the impurity incorporation is also studied. We measure the oxygen, silicon, and carbon impurity concentrations using secondary ion mass spectrometry, and measure their effect on the lattice constant by high resolution x-ray diffraction (HR-XRD). We... (More)

The ammonothermal method is one of the most promising candidates for large-scale bulk GaN growth due to its scalability and high crystalline quality. However, emphasis needs to be put on understanding the incorporation and effects of impurities during growth. This article discusses how impurities are incorporated in different growth zones in basic ammonothermal GaN, and how they affect the structural, electrical and optical properties of the grown crystal. The influence of growth time on the impurity incorporation is also studied. We measure the oxygen, silicon, and carbon impurity concentrations using secondary ion mass spectrometry, and measure their effect on the lattice constant by high resolution x-ray diffraction (HR-XRD). We determine the resulting free carrier concentration by spatially resolved Fourier transform infrared spectroscopy and study the optical properties by spatially resolved low-temperature photoluminescence. We find that oxygen is incorporated preferentially in different growth regions and its incorporation efficiency depends on the growth direction. The oxygen concentration varies from 6.3×1020 cm−3 for growth on the {112¯2} planes to 2.2×1019 cm−3 for growth on the (0001) planes, while silicon and carbon concentration variation is negligible. This results in a large variation in impurity concentration over a small length scale, which causes significant differences in the strain within the boule, as determined by HR-XRD on selected areas. The impurity concentration variation induces large differences in the free carrier concentration, and directly affects the photoluminescence intensity.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
A1. Impurities, A2. Ammonothermal crystal growth, A2. Single crystal growth, B1. Bulk GaN, B1. Nitrides
in
Journal of Crystal Growth
volume
456
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:84994096895
  • wos:000389590400008
ISSN
0022-0248
DOI
10.1016/j.jcrysgro.2016.08.040
language
English
LU publication?
yes
id
b22d0212-068c-4679-8ede-8a54b80a0172
date added to LUP
2016-12-23 07:44:46
date last changed
2017-09-18 11:32:52
@article{b22d0212-068c-4679-8ede-8a54b80a0172,
  abstract     = {<p>The ammonothermal method is one of the most promising candidates for large-scale bulk GaN growth due to its scalability and high crystalline quality. However, emphasis needs to be put on understanding the incorporation and effects of impurities during growth. This article discusses how impurities are incorporated in different growth zones in basic ammonothermal GaN, and how they affect the structural, electrical and optical properties of the grown crystal. The influence of growth time on the impurity incorporation is also studied. We measure the oxygen, silicon, and carbon impurity concentrations using secondary ion mass spectrometry, and measure their effect on the lattice constant by high resolution x-ray diffraction (HR-XRD). We determine the resulting free carrier concentration by spatially resolved Fourier transform infrared spectroscopy and study the optical properties by spatially resolved low-temperature photoluminescence. We find that oxygen is incorporated preferentially in different growth regions and its incorporation efficiency depends on the growth direction. The oxygen concentration varies from 6.3×10<sup>20</sup> cm<sup>−3</sup> for growth on the {112¯2} planes to 2.2×10<sup>19</sup> cm<sup>−3</sup> for growth on the (0001) planes, while silicon and carbon concentration variation is negligible. This results in a large variation in impurity concentration over a small length scale, which causes significant differences in the strain within the boule, as determined by HR-XRD on selected areas. The impurity concentration variation induces large differences in the free carrier concentration, and directly affects the photoluminescence intensity.</p>},
  author       = {Sintonen, Sakari and Kivisaari, Pyry and Pimputkar, Siddha and Suihkonen, Sami and Schulz, Tobias and Speck, James S. and Nakamura, Shuji},
  issn         = {0022-0248},
  keyword      = {A1. Impurities,A2. Ammonothermal crystal growth,A2. Single crystal growth,B1. Bulk GaN,B1. Nitrides},
  language     = {eng},
  month        = {12},
  pages        = {43--50},
  publisher    = {Elsevier},
  series       = {Journal of Crystal Growth},
  title        = {Incorporation and effects of impurities in different growth zones within basic ammonothermal GaN},
  url          = {http://dx.doi.org/10.1016/j.jcrysgro.2016.08.040},
  volume       = {456},
  year         = {2016},
}