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. Boron-doped diamond comprising:
a layer of diamond comprising a doped region extending into the layer from a surface, the doped region comprising substitutional boron dopant atoms, wherein
the concentration of substitutional boron dopant atoms at the surface is at least 1×10 19 cm −3 ,
the depth profile of the substitutional boron dopant atoms corresponds to a complimentary-error-function, and
the doped region comprises silicon dopant atoms at a depth of less than 5 nm from the surface.
2. The diamond of claim 1 , wherein the concentration of substitutional boron dopant atoms at the surface is at least 2×10 19 cm −3 .
3. The diamond of claim 1 , wherein the concentration of substitutional boron dopant atoms at the surface is at least 2.2×10 19 cm −3 .
4. The diamond of claim 1 , wherein the concentration of substitutional boron dopant atoms at a depth of 100 nm from the surface is no greater than 1×10 16 cm −3 .
5. The diamond of claim 1 , wherein the concentration of substitutional boron dopant atoms at a depth of 100 nm from the surface is no greater than 1×10 15 cm −3 .
6. The diamond of claim 1 , wherein the boron doped diamond is extrinsically doped with the substitutional boron dopant atoms to a depth of at least 100 nm.
7. The diamond of claim 1 , wherein the surface is free of graphitized diamond.
8. The diamond of claim 1 , wherein the diamond is natural diamond.
9. The diamond of claim 1 , wherein the diamond comprises type IIa diamond.
10. The diamond of claim 1 , wherein the diamond is single-crystalline diamond.
11. The diamond of claim 1 , wherein the diamond is single-crystalline diamond, the concentration of substitutional boron dopant atoms at the surface is at least 2×10 19 cm −3 , and the concentration of substitutional boron dopant atoms at a depth of 100 nm from the surface is no greater than 1×10 16 cm −3 .
12. The diamond of claim 1 , wherein the boron doped diamond is free of silicon dopant atoms at a depth of 5 nm or greater from the surface.
13. A method of making the substitutionally boron-doped diamond, the method comprising:
bonding a boron-doped single-crystalline silicon nanomembrane to the surface of a layer of diamond; and
annealing the diamond and the nanomembrane at a temperature of at least 700° C. for a time sufficient to allow boron dopant atoms from the nanomembrane to diffuse into the layer of diamond to form a doped region in the diamond, the doped region comprising substitutional boron dopant atoms,
wherein the concentration of substitutional boron dopant atoms at the surface is at least 1×10 19 cm −3 and the depth profile of the substitutional boron dopant atoms corresponds to a complimentary-error-function, and
further wherein silicon atoms from the nanomembrane also diffuse into the layer of diamond, such that the doped region comprises silicon dopant atoms at a depth of less than 5 nm from the surface.
14. The method of claim 13 , wherein the concentration of boron dopant atoms at the surface of the layer of diamond is at least 2×10 19 cm −3 .
15. The method of claim 13 , wherein the annealing temperature is no greater than about 1000° C.
16. The method of claim 13 , 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 membrane that is bonded to the surface of the layer of diamond.
17. The method of claim 13 , wherein the boron dopant atom concentration in the boron-doped single-crystalline silicon nanomembrane is at least 1×10 −3 at the surface of the membrane that is bonded to the surface of the layer of diamond.
18. The method of claim 13 , wherein the boron-doped single-crystalline silicon nanomembrane has a thickness of no greater than about 100 nm.
19. The method of claim 13 , wherein the boron-doped single-crystalline silicon nanomembrane has a thickness of no greater than about 500 nm.
20. The method of claim 13 , wherein the diamond is single-crystalline diamond.