A semiconductor structure is described, including a semiconductor substrate and a semiconductor layer disposed on the semiconductor substrate. The semiconductor layer is both compositionally graded and structurally graded. Specifically, the semiconductor layer is compositionally graded through its thickness from substantially intrinsic at the interface with the substrate to substantially doped at an opposite surface. Further, the semiconductor layer is structurally graded through its thickness from substantially crystalline at the interface with the substrate to substantially amorphous at the opposite surface. Related methods are also described.