A semiconductor structure comprises a substrate comprising a first crystalline semiconductor material, a dielectric layer, above the substrate, defining an opening, a second crystalline semiconductor material at least partially filling the opening, and a crystalline interlayer between the substrate and the second crystalline semiconductor material. The first crystalline semiconductor material and the second crystalline semiconductor material are lattice mismatched, and the crystalline interlayer comprises an oxygen compound. A method for fabricating semiconductor structure comprises the steps of providing a substrate including a first crystalline semiconductor material, patterning an opening in a dielectric layer above the substrate, the opening having a bottom, forming a crystalline interlayer on the substrate at least partially covering the bottom, and growing a second crystalline semiconductor material on the crystalline interlayer thereby at least partially filling the opening. The crystalline semiconductor materials are lattice mismatched, and the crystalline interlayer comprises an oxygen compound.