Japanese company Adamant Namiki Precision Jewel Co. and researchers at Saga University in Kyushu, Japan have developed a new method to mass-produce two-inch (5 cm) diamond wafers.

Although the use of diamonds is one of the most promising materials for quantum computing systems, too much nitrogen in diamond disrupts its quantum storage capabilities.

The new ultra-high purity diamond contains no more than three parts per billion of nitrogen atoms, which is required for quantum applications such as quantum computers, quantum memory and quantum sensor devices.

The diamond wafers, dubbed Kenzan Diamond, could be used for quantum memory, as the ultra-high purity of the diamond allows it to store a whopping 25 exabytes of data, the equivalent of one billion Blu-ray discs.

So far, usable diamond crystals have only been about four square millimeters in size. This new technology is expected to lead to quantum computers in the future.

Diamond wafers are made by growing crystals on a substrate material, usually on a flat surface. In the technology of growing diamond crystals, it is necessary to use nitrogen gas to obtain a high growth rate, so nitrogen impurities with a concentration of several parts per million are mixed with a diamond crystal and cannot be used in a quantum computer.

The main problem with this method is that the diamond can crack under stress, degrading its quality. In the new method, the team uses a step-shaped substrate surface that distributes stress horizontally and prevents cracking. This newly exploited surface allows them to produce larger diamond plates with higher purity.

The study will be presented at the International Conference on Composite Semiconductor Technology in May.

Adamant Namiki plans to commercialize Kenzen Diamonds in 2023 while working on doubling the plate size.