Synthesis of AlGaN and InN crystals under high pressures

AlGaNとInN結晶の高温高圧合成

齋藤 寛之; 内海 渉; 金子 洋*; 青木 勝敏

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

著者らはオプトエレクトロニクス及びパワーデバイスにおけるキーマテリアルであるIII族窒化物半導体材料の高温高圧合成を、放射光その場観察と組合せて行ってきた。AlN及びGaNの混合粉末が6.0GPa, 800Cの条件下で固相反応することを見いだし、AlGaN(0x1)の多結晶焼結体を作製した。またAlGaN試料が2400C, 6.5GPaで融解することを見いだし、その単結晶を融液徐冷により作製した。InNの高温高圧状態図を放射光その場観察から決定し、19GPa, 1900CでInNが融解することを確認した。

We have performed synthesis studies of various III-V nitrides crystals, key materials for optoelectronic and high-power/frequency devices, using a cubic-anvil-type large volume high-pressure apparatus combined with in situ X-ray diffraction. Polly-crystallines of AlGaN alloys covering a composition range of 0 x 1 were synthesized by a solid-phase reaction under high pressure. In situ X-ray diffraction profiles were measured to observe the alloying process, which started at around 800C under 6.0 GPa. Single crystal of AlGaN was also successfully obtained by slow cooling of its melt from 2400C at 6.5 GPa. For InN, its phase diagram was determined under high P-T conditions up to 20GPa and 2000C based on the in situ observations, which demonstrates that 19GPa and 1900C are needed for its congruent melting.