Preparation of Single-Crystal Isotopically Enriched 70 Ge by a Hydride Method

— Single-crystal 70 Ge germanium with high isotopic and chemical purity has been prepared by a hydride method. Germanium isotopes have been separated by centrifugation with the use of monogermane as a starting volatile substance. Isotopically enriched polycrystalline 70 Ge has been prepared by pyrolyzing 70 GeH 4 monogermane. A 70 Ge single crystal has been grown by the Czochralski technique. The resultant material has p -type conductivity and intrinsic resistivity at room temperature. The concentration of elemental impurities is under 10 –6 to 10 –5 wt %. The isotopic purity of the 70 Ge single crystal is 99.926 at % and it contains a record low concentration of the odd isotope 73 Ge: 0.00007 at %.