Any kind of reliable measurements require referencing and calibration to an ultra-precise unit system. The international system of units (SI system) was revolutionized over the last years by connecting all SI units to fundamental natural constants instead of artificial objects.

The last missing unit was the kilogram (kg) mass unit.

"Big K", the Platin-Iridium block in the French Museum Louvre in Paris defining the kg for around 130 years, had lost weight. A redefinition of the kg using fundamental constants was thus an urgent need.

For this purpose, the PTB (Physikalisch-Technische Bundesanstalt) pursued an approach of "counting" atoms in a silicon sphere.

Within the scope of the international Avogadro Project and national Kg projects, the IKZ Section Semiconductors developed (together with important Russian partners in Nischni Nowgorod) by the Float-Zone technique defect-free bulk crystals of highly enriched (up to 99.999 at%) silicon-28.

Only the IKZ with its expertise in crystal growth is able to achieve this precision in isotopically pure silicon crystal growth today.