| 主权项 |
1. A semiconductor apparatus comprising:
a substrate; a buffer layer formed on the substrate; an SLS (Strained Layer Superlattice) buffer layer formed on the buffer layer; an electron transit layer formed on the SLS buffer layer and formed of a semiconductor material; and an electron supply layer formed on the electron transit layer and formed of a semiconductor material; wherein the buffer layer includes at least three AlGaN layers with different Al composition ratios and the at least three AlGaN layers of the buffer layer are arranged in an order that the Al composition ratio decreases from a substrate side to an SLS buffer layer side, the buffer layer including a first buffer layer formed of Al0.8Ga0.2N, a second buffer layer formed of Al0.5Ga0.5N, and a third buffer layer formed of Al0.3Ga0.7N, wherein the SLS buffer layer is formed by alternately laminating a first lattice layer including AlN and a second lattice layer including GaN, and the second lattice layer in the SLS buffer layer, excluding the first lattice layer, is doped with an impurity element of Fe, the second lattice layer having a band gap smaller than a band gap of the first lattice layer, and wherein the Al composition ratio of one of the two or more AlGaN layers of the buffer layer being in contact with the SLS buffer layer is greater than or equal to an Al effective composition ratio of the SLS buffer layer. |
