X-ray studies of Si1-xGex single crystals

Abstract

Structural imperfections were studied in Si1 - xGex (1 - 9 at. % Ge) solid-solution single crystals grown using the Czochralski method. The studies were performed using x-ray diffraction topography with laboratory and synchrotron radiation sources, x-ray diffractometry, and synchrotron radiation phase radiography. In all crystals studied, irrespective of the Ge concentration, impurity bands (growth bands) were observed. An increase in the Ge concentration in the range 7 - 9 at. % was shown to bring about the nucleation and motion of dislocations on a few slip systems and the formation of slip bands. Local block structures were observed in the places where slip bands intersected. The most likely reason for the formation of slip bands is the inhomogeneous distribution of Ge atoms over the ingot diameter and along the growth axis. Therefore, the structure of Si1 - xGex solid-solution single crystals can be improved by making them more uniform in composition. (c) 2005 Pleiades Publishing, Inc.