Chemical defects of gallium oxide at low oxygen partial pressure and doping for sol-gel thin films

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06791
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: Gifu University
• Principal Investigator: Ohya Yutaka 岐阜大学, 工学部, 教授 (80167311)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 酸化ガリウム / 電気伝導度 / 格子欠陥

Outline of Final Research Achievements

The electrical conductivity of porous and high-purity β-Ga2O3 ceramics was measured as a function of oxygen partial pressure, po2, at 700 to 900℃. In the high po2 range, the conductivity was proportional to about -1/4th power of po2, while in the lower po2 range less than about 10^-5 atm its exponent was -0.1 to -0.13. This suggests that different types of defects were formed at high and low po2. The point defect of doubly ionized interstitial gallium ion causes the exponent of -1/4, the same value of the experiment in high po2. When po2 was changed, the electrical conductivity first changed sharply, followed by a slow change, suggesting a certain migrations of point defects, and so on. Many edge dislocations, with density of about 10^12 /cm2, were observed after long time duration in reducing atmosphere at 800℃.

Free Research Field

無機材料・物性

Academic Significance and Societal Importance of the Research Achievements

酸化ガリウムは次世代のパワーデバイス用の半導体基板として注目され、研究されている。半導体基板は高品質の単結晶を作製することが不可欠であるが、どの様な欠陥が生成し、これが電気的性質に影響を及ぼしているかについて明らかにする必要がある。この研究では酸化物半導体の基礎となる欠陥の生成について電気伝導度の酸素分圧依存性についての実験を行った。その結果は酸素分圧が高いときには２価に帯電した格子間ガリウムが重要な役割を果たしていることが分かった。さらに非常に高密度の刃状転移が存在しており、これが高品質な単結晶の合成に影響を及ぼすことも示された。