Nitride semiconductor wafer, nitride semiconductor element, and method for manufacturing nitride semiconductor wafer

摘要

A nitride semiconductor wafer includes a silicon substrate, a first layer, a second layer, a third layer, a fourth layer, a fifth layer, and a sixth layer. The first layer is provided on the silicon substrate. The second layer is provided on the first layer. The third layer is provided on the second layer. The fourth layer is provided on the third layer. The fifth layer is provided on the fourth layer. The sixth layer is provided on the fifth layer. A composition ratio x4 of the fourth layer decreases in a first direction from the third layer toward the fifth layer. A maximum value of the composition ratio x4 is not more than a composition ratio of the third layer. A minimum value of the composition ratio x4 is not less than a composition ratio of the fifth layer.

主权项

1. A nitride semiconductor element, comprising:
a silicon substrate; a foundation layer including:
a first layer of Alx1Ga1-x1N (0.8≦x1≦1) provided on the silicon substrate;a second layer of Alx2Ga1-x2N (0.7≦x2<0.8) provided on the first layer;a third layer of Alx3Ga1-x3N (0.4≦x3≦0.6) provided on the second layer;a fourth layer of Alx4Ga1-x4N provided on the third layer;a fifth layer of Alx5Ga1-x5N (0.1≦x5≦0.2) provided on the fourth layer; anda sixth layer of Alx6Ga1-x6N (0≦x6