System for forming SiC crystals having spatially uniform doping impurities

1. A physical vapor transport growth system comprising, in combination:

a growth chamber charged with source material and a seed crystal in spaced relation;

a first porous capsule having in addition to the pores thereof at least one calibrated capillary of predetermined dimensions extending between an interior thereof and an exterior thereof, wherein an interior of the first capsule is charged with a first dopant, each calibrated capillary is sized for controlled effusion of dopant at a temperature between 1900° C. and 2400° C., and an exterior of the first capsule is positioned on or in the source material in the growth chamber; and

at least one heating element operative for heating the interior of the charged growth chamber and the first capsule positioned therein to a desired reaction temperature whereupon the source material forms a crystal on the seed crystal and the formed crystal is doped with the first dopant via controlled effusion of the first dopant through the calibrated capillary in the first capsule.

2. The system of claim 1 , further including a second porous capsule having in addition to the pores thereof at least one calibrated capillary of predetermined dimensions extending between an interior thereof and an exterior thereof, wherein:

an interior of the second capsule is charged with a second dopant and an exterior of the second capsule is positioned on or in the source material in the growth chamber; and

in response to heating the interior of the charged growth chamber and the second capsule positioned therein to the desired reaction temperature, the formed crystal is doped with the second dopant via controlled effusion of the second dopant through the calibrated capillary in the second capsule.

3. The system of claim 2 , wherein the first and second dopants are the same.

4. The system of claim 1 , wherein either the growth chamber, the capsule, or both is made of a material that is not reactive with the source material or the dopant.

5. The system of claim 4 , wherein the material forming the growth chamber and/or the capsule is graphite.

6. The system of claim 1 , wherein the chemical form of the dopant is elemental, carbide, or silicide.

7. The system of claim 1 , wherein the dopant includes at least one of the following: vanadium, aluminum, boron and phosphorus.

8. The system of claim 1 , wherein the growth chamber is charged with the source material in a powder form.

9. The system of claim 1 , wherein the source material includes SiC.