Composite Defect Engineering of Diamond Single Crystals under High Pressure

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21096
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: National Institute for Materials Science
• Principal Investigator: TANIGUCHI Takashi 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 拠点長 (80354413)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: ダイヤモンド / 高圧合成 / 複合欠陥

Outline of Final Research Achievements

After establishing high-pressure synthesis conditions to control the nitrogen concentration in diamond at the 0.1-100 ppm level, single crystals with nitrogen and boron co-doped in the 1-10 pm region were synthesized by adding trace amounts of boron. Nitrogen concentration was evaluated by the ESR method according to the concentration of P1 centers that substituted carbon atoms in the crystal, and boron concentration was evaluated by SIMS analysis. Nearly colorless diamond crystals in the intermediate region were obtained, along with yellow to blue diamond crystals with nitrogen excess and boron excess.
Furthermore, the addition of Sn as a dissimilar element produced significant recrystallized graphite and good quality diamond single crystals at the same time. It remains to be evaluated whether the new color centers observed are derived from Sn or not.

Free Research Field

高圧力材料科学

Academic Significance and Societal Importance of the Research Achievements

硬度、熱伝導率等が最大のダイヤモンドにおいて、過去に未踏の大きな格子 ミスフィットを伴うドーピングへの自由度が得られれば飛躍的な機能応用展開が期待できる。ダイヤモンド中の主たる不純物は炭素の両隣のホウ素(B)と窒素（N）であり、ダイヤモンド中にBとNが固溶する際、B-Nペアの形成が安定と予想される。育成溶媒の最適化による窒素濃度の制御と精密なホウ素添加量の制御により、1～10ppmレンジでB-N共添加のほぼ無色のダイヤモンド結晶を得た。SIMS分析とESR分析により、結晶中でB-Nペアの形成が示唆される。高圧下でのダイヤモンドへのB－N複合欠陥の導入はドーピング自由度の拡張として期待できる。