Enlargement of defect-free GaN crystals by the Na-flux method

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K14138
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 30010:Crystal engineering-related
• Research Institution: Osaka University
• Principal Investigator: Imanishi Masayuki 大阪大学, 工学研究科, 助教 (00795487)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 低転位 / 高純度化 / ポイントシード / 高速成長

Outline of Final Research Achievements

In order to improve the reliability and practical use of GaN-based devices with excellent energy-saving characteristics, it is necessary to improve the quality of GaN crystals. In this application study, we developed the high-quality GaN crystal growth technology recently discovered by the applicants, and worked on the establishment of further high-purity and large-diameter technology. High-speed growth has been realized by enabling continuous growth in a thin liquid with a high nitrogen concentration, which had not been realized until now. In addition, we succeeded in significantly reducing the oxygen concentration in the crystal by adding lithium. This method can be expected to be a highly practical method that can be sufficiently applied to future mass production processes.

Free Research Field

結晶工学

Academic Significance and Societal Importance of the Research Achievements

現在GaN基板製造の主流となっているのはHVPE法であり、高純度かつ大口径のGaN結晶が得られているが、1cm角あたり10の6乗個程度の転位が残存してしまう。最も低転位化に成功している手法は、Naフラックス法同様の液相成長であるアモノサーマル法であり、1cm角あたり10の4乗個以下まで低転位化を実現しているが、不純物の低減が課題である。本研究において従来法では実現できなかった、1cm角あたり10の4乗個以下の低転位、高純度を全て同時に満たすことを可能にする手法を開発した。