Si（111）基板上AlGaN／GaN HEMT構造の多層膜構造検討による厚膜化

摘要

Si基板上AIGaN／GaN HEMTについて多層膜構造の検討により厚膜化を図った。多層膜構造をAlGaN／GaN，GaN／AlN，AlGaN／AlN　としてウエハーの反り量を測定したところ、反りの大小関係はAlGaN／GaN、GaN／AlN、AlGaN／AlNの順で小さく、多層膜の平均Al組成が高いほど小さいことがわかった。これは、GaNと多層膜の格子定数差に起因した圧縮歪がGaN層に発生したためと考えられる。表面クラックについては多層膜構造をAlGaN／AlNとしたところ、総膜厚が6μm程度までクラックフリーを達成できた。%The study of AlGaN/GaN HEMTs by growing thick GaN on Si substrate was demonstrated using multilayer structure. The various multilayers grown were namely AlGaN/GaN, GaN/AlN and AlGaN/AlN and the bowing parameters of the AlGaN/GaN grown were studied. The bowing parameters were found to decrease as we move from pairs of AlGaN/GaN, GaN/AlN and AlGaN/AlN with increased Al concentration. This is due to the compression strain that originated from the difference in the lattice constant between GaN and the multilayer structure. By using the AlGaN/AIN multilayer structure, a total film thickness as high as 6 urn was achieved without cracks.