Patent ID: 11387356

Abstract:
A semiconductor structure includes a seed layer on a substrate and an epitaxial stack on the seed layer. The epitaxial stack includes a first superlattice part and a second superlattice part on the first superlattice part. The first superlattice part includes first units repetitively stacked M1 times on the seed layer. Each first unit includes a first sub-layer that is an Aly1Ga1-y1N layer, and a second sub-layer that is an Alx1Ga1-x1N layer, wherein y1<x1. The second superlattice part includes second units repetitively stacked M2 times on the first superlattice part. Each second unit includes a third sub-layer that is an Aly2Ga1-y2N layer, and a fourth sub-layer that is an Alx2Ga1-x2N layer, wherein y2<x2. M1 and M2 are positive integers, 0≤x1, y1 and y2<1, 0<x2≤1, and x1<x2, or x1=x2 and y1<y2.