Abstract: A semiconductor power device, comprising: a substrate; a first semiconductor layer with a first lattice constant formed on the substrate; a first grading layer formed on the first semiconductor layer and comprising a first portion; a second grading layer formed on the first grading layer; a second semiconductor layer with a second lattice constant formed on the second grading layer; a first interlayer formed in the first grading layer and adjacent to the first portion of the first grading layer; and a second interlayer formed in the second grading layer; wherein the first interlayer comprises a first superlattice including a series of Alx1Ga1-x1N/Aly1Ga1-y1N alternate layers, (x1-y1)?0.2, and the second interlayer comprises a second superlattice including a series of Alx2Ga1-x2N/Aly2Ga1-y2N alternate layers, (x2-y2)?0.2, wherein the average of x1 and y1 is larger than that of x2 and y2.

Abstract: A semiconductor power device, comprising: a substrate; a first semiconductor layer with a first lattice constant formed on the substrate, wherein the first semiconductor layer comprises a first group III element; a first grading layer formed on the first semiconductor layer and comprising a first portion; a second semiconductor layer with a second lattice constant formed on the first grading layer, wherein the second semiconductor layer comprises a second group III element; and a first interlayer formed in the first grading layer and adjacent to the first portion of the first grading layer, wherein a composition of the first interlayer is different from that of the first portion, and the first grading layer comprises the first group III element and the second group III element, and concentrations of both the first group III element and the second group III element in the first grading layer are gradually changed.