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We synthesized a mosaic diamond wafer 2 in. in size (40 × 60 mm2), which consisted of 24 single-crystal diamond (SCD) plates 10 × 10 mm2 in area, by using microwave plasma chemical vapor deposition. Even by using a cloning technique, cracking frequently occurred and the non-uniformity was remarkable for wafers that were larger than 1 in. in size. This has not been observed in smaller samples before. Appropriate crystallographic directions could avoid the cracking and is one of the predominant factors in fabricating large area SCD wafers. Comparison with numerical simulations highlighted the importance of uniformity of the substrate temperature distribution on the uniformity of the growth.

We fabricated so-called mosaic single-crystal-diamond (SCD) wafers that consist of SCD sub-crystals with identical characteristics. These sub-crystal clones were obtained from a SCD seed crystal by repeating the lift-off process using ion implantation. We found that the junctions between the cloned sub-crystals were smoothly covered and no abnormal crystal growth occurred along the junctions. Therefore, the lift-off process can be applied to the production of freestanding SCD wafers with the same size. Based on these findings, we have succeeded in synthesizing 1 in. mosaic diamond wafers.

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