Semiconductor heterostructures having reduced dislocation pile-ups and related methods

A method comprising:

• forming a relaxed seed layer over a first crystalline material of a substrate, the relaxed seed layer being a compositionally uniform second crystalline material, a composition of the second crystalline material being different from a composition of the first crystalline material and being different from a composition of a third crystalline material adjoining and overlying the relaxed seed layer;
• forming a graded layer over the relaxed seed layer;
• and
• forming a strained layer over the graded layer.

A method comprising:

• forming a seed layer on a substrate, the seed layer comprising a compositionally uniform portion, a composition of the compositionally uniform portion being different from a composition of a material adjoining and underlying the seed layer and from a composition of a material adjoining and overlying the seed layer;
• forming a graded layer over the seed layer;
• and
• forming a strained layer over the graded layer.