| CPC C30B 29/403 (2013.01) [C30B 23/02 (2013.01)] | 20 Claims |

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1. A crystal boule comprising a single-crystalline AlN portion and a plurality of single-crystalline tungsten (W) inclusions disposed within a volume of the crystal boule, wherein a total concentration of W within the crystal boule ranges from 1 ppm to 500 ppm by weight.
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