Semiconductor multilayer structure, semiconductor device and HEMT device

摘要

A semiconductor device includes an underlying layer made of a group-III nitride containing at least Al and formed on a substrate, and a group of stacked semiconductor layers including a first semiconductor layer made of a group-III nitride, preferably GaN, a second semiconductor layer made of AlN and a third semiconductor layer made of a group-III nitride containing at least Al, preferably Al_xGa_1-xN where x>=0.2. The semiconductor device suppresses the reduction in electron mobility resulting from lattice defects and crystal lattice randomness. This achieves a HEMT device having a sheet carrier density of not less than 1x10¹³/cm² and an electron mobility of not less than 20000 cm²/V.s at a temperature of 15 K.