Silicon-28-Tetrafluoride as an Educt of Isotope-Engineered Silicon Compounds and Bulk Materials for Quantum Systems

This review provides a summary of the existing literature on a crucial raw material for the production of isotopically pure semiconductors, which are essential for the development of second-generation quantum systems. Silicon-28-tetrafluoride (28SiF4) is used as an educt for several isotope-engineered chemicals, such as silane-28 (28SiH4) and silicon-28-trichloride (28SiHCl3), which are needed in the pursuit of various quantum technologies. We are exploring the entire chain from the synthesis of 28SiF4 to quantum applications. This includes the chemical properties of SiF4, isotopic enrichment, conversion to silanes, conversion to bulk 28Si and thin films, the physical properties of 28Si (spin neutrality, thermal conductivity, optical properties), and the applications in quantum computing, photonics, and quantum sensing techniques.

Progress and perspectives in high-purity substance production for semiconductor industry

In the last decade, novel approaches for post-synthesis processes of separation and high purification of gases are gaining larger acceptance in industry. The market is competing with consolidated operations such as cryogenic distillation. The key for new approaches of distillation, membranes and crystallization in challenging and harsh environments is the development of new tough, high-performance materials that are characterized by higher energy efficiency compared with conventional cryogenic distillation. This review highlights the most promising fields of research in high purification and separation of gases by considering the elevated pressure and thermal distillations, membrane cascades, purification in synthesis by use of catalytic technologies, crystallization and hydride methods based on them.

Refractive index spectral dependence, Raman spectra, and transmission spectra of high-purity 28Si, 29Si, 30Si, and natSi single crystals

We performed precise measurement of the refractive index of stable silicon isotopes 28Si, 29Si, and 30Si single crystals with enrichments above 99.9 at.% and a silicon single-crystal natSi of natural isotopic composition with the Fourier-transform interference refractometry method from 1.06 to more than 80 μm with 0.1 cm(-1) resolution and accuracy of 2×10(-5)…1×10(-4). The oxygen and carbon concentrations in all crystals are within 5×10(15) cm(-3), and the content of the metal impurities is 10(-5)…10(-6) at.%. The peculiar changes of the refractive index in the phonon absorption region of all silicon single crystals are shown. The coefficients of the generalized Cauchy dispersion function approximating the experimental refractive index values all over the measuring range are given. The transmission and Raman spectra are also studied.