| Zugriffsnummer | 18366 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | Silicon for primary metrology: the effect of hydrogen on its perfection |
| Autor(in); Institution |
Becker, Peter; 4.3, Quantenoptik und Längeneinheit, PTB-Braunschweig
Bettin, Horst; 3.3, Chemisch-physikalische Stoffeigenschaften, PTB-Braunschweig
Kuetgens, Ulrich; 4.3, Quantenoptik und Längeneinheit, PTB-Braunschweig
Hallmann-Seiffert, B.; Institut für Kristallzüchtung, Berlin, GERMANY
Riemann, H.; Institut für Kristallzüchtung, Berlin, GERMANY
|
| Quelle/Jahr | Journal of Physics D: 38 (2005), 22, 4109 - 4114 |
| ISSN | 0022-3727 |
| DOI | |
| Zusammenfassung | One possible basis of a new definition of the kilogram is the Avogadro constant determined by measuring lattice parameter and molar volume of a silicon single crystal. Data of molar volumes derived from different silicon crystals in the international framework differ significantly. Presumably, the differences are produced by holes or voids in the crystal lattice exceeding today’s experience in silicon perfection. To illuminate this problem, test crystals were grown in different ambient conditions in order to generate areas in the material with vacancies or light elements. Macroscopic defects were generated by hydrogen in the growth atmosphere and detected by preferential etching, laser scattering tomography and x-ray topography. Using the pressure-of-flotation method for the evaluation of density differences in silicon, relative loss in the macroscopic density of FZ silicon up to 1 × 10-7 was observed when the growth ambient contained 2% hydrogen. The reason for reported molar volume differences in the order of 10-6 is still not found and will be the subject of further investigations. |
