Nitride semiconductor device, nitride semiconductor wafer and method for manufacturing nitride semiconductor layer

摘要

According to one embodiment, a nitride semiconductor device (111,112) includes: a foundation layer (10i) formed on an Al-containing nitride semiconductor layer (50) which is formed on a silicon substrate (40), the foundation layer (10i) including GaN; and a functional layer (10s) provided on the foundation layer (10i), the functional layer (10s) including a first semiconductor layer (10), which has an impurity concentration higher than an impurity concentration of the foundation layer (10i), and includes GaN of a first conductivity type. The Al-containing nitride semiconductor layer (50) includes a multilayer structure body (53) including a plurality of alternating second layers (52) and third layers (51). The second and third layers include nitride semiconductor. An Al composition ratio of the third layer (51) is lower than an Al composition ratio of the second layers (52). A thickness of the foundation layer (10i) is larger than a thickness of the third layer (51) and smaller than a thickness of the first semiconductor layer (10).