The Leibniz-Institut für Kristallzüchtung (IKZ) is strengthening its collaboration with a company by establishing supply agreements for high-purity semiconductor materials. These materials will be further studied for their potential applications in quantum technologies worldwide.

High-speed silicon-germanium chips and measurements probes can be seen inside a cryogenic probe station in a laboratory at the Georgia Institute of Technology.

Quantum technologies have the power to revolutionize several areas, such as computer processing capacity, simulation performance, sensor systems, and optics precision. To realize these advancements, reliable materials are needed to facilitate the desired quantum effects. Prof. Thomas Schröder, the Director of IKZ, explains that silicon, which serves as the foundation for today's microelectronics, is a powerful material platform being explored for integration with quantum technologies.

A promising material for this integration is silicon germanium (SiGe), which has been used in high-frequency technology since the 1990s and, more recently, in silicon photonics. However, the quality of the currently available SiGe material is inadequate for quantum technology applications. The reason for this limitation lies in the presence of various isotopes within the material, each possessing slightly different masses and, therefore, partially unbalanced nuclear spins. To ensure the highest quality, isotopically pure silicon-28 and germanium-72 crystals are required.

IKZ, well-versed in the growth of high-purity crystals, has now entered into a supply agreement with Dr. Eberl MBE-Komponenten GmbH to obtain these high-potential semiconductor materials. The agreement includes strict export controls and aligns with IKZ's mission to not only conduct research and development of innovative materials but also produce them in sufficient quantities for other researchers. Dr. Eberl MBE-Komponenten GmbH will handle the global distribution of these materials since IKZ does not maintain a customer network for worldwide product offerings. Furthermore, due to the significant cost difference (a factor of 1000) between isotopically pure silicon and germanium crystals compared to regular elements, Dr. Eberl MBE-Komponenten GmbH possesses cutting-edge equipment technologies for precise deposition on chips, thereby reducing expensive material losses.

In quantum computing, the electrons within semiconductors must attain a specific state: pairs of electrons must be quantum mechanically entangled, and their spins must not be identical. To maintain this entangled state for an adequate duration, disturbances from isotopes with nuclear spins must be avoided in the semiconductor material. Therefore, only atoms with an even number of nucleons, such as silicon-28 and germanium-72, are suitable for these applications.

To produce isotopically pure silicon-28, the atoms are separated based on their atomic mass through centrifugation in large plants. Similar sorting processes are applied to natural germanium. At IKZ, high-purity Si and Ge crystals are grown from the sorted material and subsequently purified to remove impurities caused by process gases. IKZ has developed expertise in this field through extensive research collaboration with Germany's national metrology institute, Physikalisch-Technische Bundesanstalt (PTB). In fact, PTB and IKZ jointly worked on the worldwide redefinition of the kilogram and created the perfectly polished isotopically pure silicon-28 sphere, weighing exactly one kilogram, which provides a new reference standard for the unit of measurement.

Dr. Eberl MBE-Komponenten GmbH, a medium-sized company located near Stuttgart, specializes in the development and production of ultra-high vacuum systems, specifically molecular beam epitaxy systems. These systems facilitate the synthesis of epitaxial materials, enabling the production of semiconductors for various applications in nano- and optoelectronics, thin solar cells, quantum materials, oxide films, and nanostructures like graphene. The IKZ and Dr. Eberl MBE-Komponenten GmbH have a long-standing research partnership and have collaborated on the development, specification, and patenting of these systems.

Together, with the availability of isotopically pure Si and Ge materials, Dr. Eberl MBE-Komponenten GmbH is well-positioned to offer comprehensive services to customers in the field of quantum technologies worldwide.