X−ray topography of defects produced after heat treatment of dislocation−free silicon containing oxygen

Abstract

In this investigation we have established the nature of defects produced by the heat treatment of initially dislocation−free silicon crystals containing oxygen. The defects observed by x−ray topography are of two types: (i) prismatic loops with Burgers vector along 〈110〉 and (ii) stacking faults with Burgers vector along 〈111〉. Fringe contrast has been observed in the partial dislocation loops. The contrast and geometrical nature of the fringes in section patterns has been analyzed using the results of dynamical theory of x rays for stacking faults. From detailed theoretical calculations and experimental observations of section topographs we have been able to establish the nature of the stacking faults. All of the faults investigated have been of the Frank extrinsic type. An important result of this investigation has been that the stacking fault fringe information on the section pattern can under certain circumstances be obscured on traverse topographs. Conclusions on the nature of the fault based solely on traverse topography can be erroneous and may lead to exactly the opposite conclusion to that based on section topographs. The importance of section topographs is underscored in this study.