Patent ID: 7622372

Claim:
A method, comprising: a) bombarding a semiconductor layer structure with high energy ions, wherein the semiconductor layer structure has a front surface and a back surface, and wherein the front surface comprises at least one layer of single crystalline semiconductor material supported on a support wafer, and wherein the semiconductor layer structure comprises at least two materials, and wherein the front surface of the semiconductor layer structure is bombarded with a dose of high energy ions sufficient to introduce an excess of vacancies into the at least one single crystalline semiconductor material near the front surface of the at least one single crystalline semiconductor material, and wherein the at least one single crystalline semiconductor material remains single crystalline during and after the bombardment; then b) implanting a first dopant material into the front surface of the at least one single crystalline semiconductor material by using low energy ion implantation; then c) annealing the semiconductor layer structure; wherein the excess of vacancies near the front surface of the at least one single crystalline semiconductor material is sufficient to reduce dopant material diffusion and allow the dopant material to remain close to the front surface of the at least one single crystalline semiconductor material and to form doped crystalline semiconductor layer forming a junction wherein the junction depth is less than 20 nm from the front surface of the at least one single crystalline semiconductor material and wherein the sheet resistance of the annealed doped crystalline semiconductor layer is less than 500 ohms/square.