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平成29年度衝撃波シンポジウム (2018年3月7日-9日. 東北大学片平さくらホール ）仙台市, 宮城県, (2018年3月7日-9日. 宇宙航空研究開発機構角田宇宙センター ）角田市, 宮城県, Symposium on Shock Waves in Japan, FY2017 (March 7-9, 2018. Sakura Hall), Sendai, Miyagi, (March 7-9, 2018. Kakuda Space Center, Japan Aerospace Exploration Agency (JAXA)(KSPC)), Kakuda, Miyagi, 資料番号: SA6000119151, レポート番号: P-21

サファイア基板を用いたコランダム構造の酸化物半導体について、適切なバッファ層を導入しミストCVD法による成長条件を明らかにした。中でも、$alpha$-In$_2$O$_3$層はサファイア基板上の$alpha$-Ga$_2$O$_3$をバッファ層として、パワーデバイス応用につながりうる結晶性および電気的特性を示した。$alpha$-In$_2$O$_3$を用いたMOSFETは明確なピンチオフ特性を示し、ドレイン電流のオンオフ比10$^6$、および電界効果移動度および有効移動度それぞれ60および217 cm$^2$/Vsの値を示した。 このように、ミストCVDを用いて半導体-絶縁構造を形成することは、低コストのデバイス応用に対して有効であるといえる。, Growth of corundum-structured oxide semiconductors has been demonstrated using appropriate buffer layers on sapphire by mist CVD. Emphasis was given for $alpha$-In$_2$O$_3$ allowing reasonable crystalline and electrical properties for power device applications with the use of an $alpha$-Ga$_2$O$_3$ buffer layer on sapphire. An $alpha$-In$_2$O$_3$MOSFET showed the clear pinch-off characteristics with the field effect mobility and effective mobility of 60 and 217 cm$^2$/Vs, respectively. together with the on-off ratio of drain current of 10$^6$. The use of mist CVD for the insulator-semiconductor structure was advantageous for low-cost devices.

Indium tin oxide and activated carbon were mixed and heated to 927^oC in a nitrogen flow from the top. After heating, crystals containing indium were formed on the YSZ substrate at the lower position at 200^oC. It was confirmed that indium was recovered in the form of indium compound from an indium tin oxide. The mixed powder of gallium nitride and activated carbon was placed in the reaction tube (Tamman tube with a hole at the bottom) and heated to 1150^oC in a nitrogen flow from the bottom. After heating, the needle-shaped crystals were formed on the gallium oxide substrate at the upper position at 600 o^C in the reaction tube. Gallium and oxygen were detected in the crystals. It was confirmed that gallium was recovered in the form of gallium oxide crystals from a ixture of gallium nitride and activated carbon.