Thermal diffusion doping of diamond
Boron-doped diamond and methods for making it are provided. The doped diamond is made using an ultra-thin film of heavily boron-doped silicon as a dopant carrying material in a low temperature thermal diffusion doping process.
1. A method of making substitutionally boron-doped diamond, the method comprising:
bonding a flexible, boron-doped, single-crystalline silicon nanomembrane to the surface of a layer of diamond; and
annealing the diamond and the boron-doped, single-crystalline silicon nanomembrane for a time sufficient to allow boron dopant atoms from the boron-doped, single-crystalline silicon nanomembrane to diffuse into the layer of diamond to form a doped region in the diamond.
2. The method of claim 1 , wherein annealing the diamond and the boron-doped, single-crystalline silicon nanomembrane comprises annealing the diamond and the boron-doped, single-crystalline silicon nanomembrane at a temperature of at least 700° C.
3. The method of claim 1 , wherein the concentration of boron dopant atoms at the surface of the layer of diamond after annealing is at least 1×10 18 cm −3 .
4. The method of claim 1 , wherein the concentration of boron dopant atoms at the surface of the layer of diamond after annealing is at least 1×10 19 cm −3 .
5. The method of claim 1 , wherein the concentration of boron dopant atoms at the surface of the layer of diamond after annealing is at least 2×10 19 cm −3 .
6. The method of claim 1 , wherein the annealing temperature is no greater than about 1000° C.
7. The method of claim 1 , wherein the boron dopant atom concentration in the boron-doped, single-crystalline silicon nanomembrane is at least 1×10 19 cm −3 at the surface of the boron-doped, single-crystalline silicon nanomembrane that is bonded to the surface of the layer of diamond.
8. The method of claim 1 , wherein the boron dopant atom concentration in the boron-doped, single-crystalline silicon nanomembrane is at least 1×10 20 cm −3 at the surface of the boron-doped, single-crystalline silicon nanomembrane that is bonded to the surface of the layer of diamond.
9. The method of claim 1 , wherein the boron-doped, single-crystalline silicon nanomembrane has a thickness of no greater than about 1000 nm.
10. The method of claim 1 , wherein the boron-doped, single-crystalline silicon nanomembrane has a thickness of no greater than about 500 nm.
11. The method of claim 1 , wherein the diamond is single-crystalline diamond.
12. The method of claim 1 , wherein the surface of the boron-doped diamond is not graphitized by the annealing the diamond and the boron-doped, single-crystalline silicon nanomembrane.
13. The method of claim 1 , further comprising doping the single-crystalline silicon nanomembrane with boron via boron ion implantation and then annealing the single-crystalline silicon nanomembrane to form the boron-doped, single-crystalline silicon nanomembrane.
14. The method of claim 13 , wherein the single-crystalline silicon nanomembrane that is doped with boron via boron ion implantation is the device layer of a silicon-on-insulator wafer, and the method further comprises releasing the boron-doped, single-crystalline silicon nanomembrane from the silicon-on-insulator wafer to form the flexible, boron-doped, single-crystalline silicon nanomembrane.