Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions

Tashiro, Tomoki; Imanishi, Masayuki; Washida, Shogo; Murakami, Kosuke; Usami, Shigeyoshi; Maruyama, Mihoko; Yoshimura, Masashi; Mori, Yusuke

doi:https://doi.org/10.1063/5.0325218

Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions

Tashiro, Tomoki; Imanishi, Masayuki; Washida, Shogo et al.

Journal of Applied Physics, 2026, 139(16), 165702

アクセス数:162件（2026-07-01 17:25 集計）

固定URL: https://hdl.handle.net/11094/104908

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タイトル	Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions
著者	著者名 Tashiro, Tomoki
	NRID 1000000795487 1000000795487 ORCID 0000-0001-9395-1750 0000-0001-9395-1750 researchmap permalink Na-flux Na-flux Scopus Author ID 55361211900 55361211900 著者名 Imanishi, Masayuki
	ORCID 0009-0004-1164-1476 0009-0004-1164-1476 Scopus Author ID 58701582300 58701582300 著者名 Washida, Shogo
	著者名 Murakami, Kosuke
	NRID 1000030897947 1000030897947 ORCID 0000-0002-9710-1718 0000-0002-9710-1718 researchmap permalink s_usami s_usami Scopus Author ID 56770778200 56770778200 著者名 Usami, Shigeyoshi
	NRID 1000020623903 1000020623903 ORCID 0000-0002-3453-8007 0000-0002-3453-8007 researchmap permalink marumarumi marumarumi Scopus Author ID 35307485800 35307485800 著者名 Maruyama, Mihoko
	NRID 1000060314382 1000060314382 ORCID 0000-0002-0770-1251 0000-0002-0770-1251 researchmap permalink read0191199 read0191199 Scopus Author ID 7403136552 7403136552 著者名 Yoshimura, Masashi
	NRID 1000090252618 1000090252618 ORCID 0000-0003-2952-7458 0000-0003-2952-7458 researchmap permalink mori_yusuke mori_yusuke Scopus Author ID 7404197134 7404197134 著者名 Mori, Yusuke
内容	Tashiro T., Imanishi M., Washida S., et al. Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions. Journal of Applied Physics 139, 165702 (2026); https://doi.org/10.1063/5.0325218.
抄録	The Na–flux method is suitable for producing large-diameter GaN substrates using the multi-point seed (MPS) method, in which numerous tiny seed crystals are arrayed on sapphire; however, a major challenge is achieving both stable growth on MPS substrates and suppression of polycrystalline formation outside the seed region. In this study, we investigated high-temperature, high N₂ pressure (HTHP) conditions, which are expected to expand the range of conditions under which only the seed crystals grow without polycrystalline formation. In short-duration growth experiments, we compared the feasibility of crystal growth on MPS substrates and the supersaturation behavior under various temperature and pressure conditions. Stable crystal growth on MPS substrates was achieved under HTHP conditions even at supersaturation levels where growth was not possible under conventional conditions. Furthermore, polycrystalline formation tended to be suppressed even under conditions, exhibiting relatively high supersaturation. Moreover, we conducted long-duration growth experiments incorporating planarization and thick-film growth using the flux-film-coated method. The polycrystalline yield was reduced to approximately 1% under HTHP conditions (900 °C/5 MPa), compared with approximately 11% under conventional conditions (870 °C/3 MPa). These results demonstrate that HTHP conditions suppress polycrystalline formation by expanding the growth region without polycrystals, thereby contributing to the development of a Na–flux GaN substrate fabrication process.
出版者	American Institute of Physics
収録物名	Journal of Applied Physics
巻(号)	139(16)
ページ	165702
刊行年月	2026-04-22
言語	英語
ハンドルURL	https://hdl.handle.net/11094/104908
PISSN	00218979
eISSN	10897550
関連情報 (isIdenticalTo)	DOI (出版社版) https://doi.org/10.1063/5.0325218
アクセス権	embargoed access
権利情報	The full-text file will be made open to the public on 22 April 2027 in accordance with the publisher's policy.
出版タイプ	Version of Record
カテゴリ	学術雑誌論文 Journal Article

資源タイプ	学術雑誌論文
ローカル資源タイプ	学術雑誌論文
DCMI資源タイプ	text
DCTERMS.bibliographicCitation	Journal of Applied Physics. 2026, 139(16), p. 165702
DC.title	Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions
DC.creator	Tashiro, Tomoki
	Imanishi, Masayuki
	Washida, Shogo
	Murakami, Kosuke
	Usami, Shigeyoshi
	Maruyama, Mihoko
	Yoshimura, Masashi
	Mori, Yusuke
DC.publisher	American Institute of Physics
DC.language' scheme='DCTERMS.RFC1766	英語
DC.type' scheme='DCTERMS.DCMIType	text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2026-04-22
DC.identifier	https://doi.org/10.1063/5.0325218
DC.description	Tashiro T., Imanishi M., Washida S., et al. Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions. Journal of Applied Physics 139, 165702 (2026); https://doi.org/10.1063/5.0325218.
DCTERMS.abstract	The Na–flux method is suitable for producing large-diameter GaN substrates using the multi-point seed (MPS) method, in which numerous tiny seed crystals are arrayed on sapphire; however, a major challenge is achieving both stable growth on MPS substrates and suppression of polycrystalline formation outside the seed region. In this study, we investigated high-temperature, high N₂ pressure (HTHP) conditions, which are expected to expand the range of conditions under which only the seed crystals grow without polycrystalline formation. In short-duration growth experiments, we compared the feasibility of crystal growth on MPS substrates and the supersaturation behavior under various temperature and pressure conditions. Stable crystal growth on MPS substrates was achieved under HTHP conditions even at supersaturation levels where growth was not possible under conventional conditions. Furthermore, polycrystalline formation tended to be suppressed even under conditions, exhibiting relatively high supersaturation. Moreover, we conducted long-duration growth experiments incorporating planarization and thick-film growth using the flux-film-coated method. The polycrystalline yield was reduced to approximately 1% under HTHP conditions (900 °C/5 MPa), compared with approximately 11% under conventional conditions (870 °C/3 MPa). These results demonstrate that HTHP conditions suppress polycrystalline formation by expanding the growth region without polycrystals, thereby contributing to the development of a Na–flux GaN substrate fabrication process.
DC.rights	The full-text file will be made open to the public on 22 April 2027 in accordance with the publisher's policy.
DC.format	104908
citation_title	Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions
citation_author	Tashiro, Tomoki
	Imanishi, Masayuki
	Washida, Shogo
	Murakami, Kosuke
	Usami, Shigeyoshi
	Maruyama, Mihoko
	Yoshimura, Masashi
	Mori, Yusuke
citation_publisher	American Institute of Physics
citation_language	英語
citation_date	2026-04-22
citation_journal_title	Journal of Applied Physics
citation_volume	139
citation_issue	16
citation_firstpage	165702
citation_doi	https://doi.org/10.1063/5.0325218
citation_public_url	https://hdl.handle.net/11094/104908

Suppression of polycrystalline formation during Na–flux GaN growth on point seeds via high-temperature and high N₂ pressure conditions

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