Single crystal growth of gallium nitride by slow-cooling of its congruent melt under high pressure

高圧下における一致溶融融液徐冷による窒化ガリウム単結晶の育成

齋藤 寛之; 内海 渉; 金子 洋*; 桐山 幸治*; 青木 勝敏

Saito, Hiroyuki; Utsumi, Wataru; Kaneko, Hiroshi*; Kiriyama, Koji*; Aoki, Katsutoshi

高圧下融液の徐冷による窒化ガリウム単結晶の育成に成功した。6.0GPa以上の圧力を加えると分解を押さえて2220Cで融液が得られることを放射光その場観察により見いだした。育成された単結晶試料のX線ロッキングカーブ測定の半値幅は30秒以下で、転位密度が小さい良質の単結晶であることが予想される。

Single crystals of GaN were successfully synthesized by slowly cooling its stoichiometric melt under high pressure. Applying high pressures above 6.0 GPa prevented decomposition and allowed the congruent melt of GaN at 2220C, which was confirmed by an in situ X-ray diffraction study. Using a cubic-anvil-type, large volume, high-pressure apparatus and a GaN powder as a starting material, single crystal growth was achieved by reducing the temperature from 2400C at 6.5 GPa. The X-ray rocking curve of the recovered sample showed a very narrow line width, less than 30 arcsec, suggesting a low dislocation density. Bulk specimens of AlGaN alloys, which covered a composition range of 0x1 were also synthesized under high pressures.