CCDS FOR X-RAY TOPOGRAPHY AT SYNCHROTRONS

An X-ray sensitive CCD camera has been evaluated at the Daresbury Sync hrotron Radiation Source (SRS) for use in X-ray topographic (XRT) stud ies of epitaxially grown, strain-layered semiconductors (InGaAs/GaAs). Current topographic images obtained with photographic emulsion plates require considerable exposure and processing times of up to an hour s o that real-time XRT cannot be realised. However, results from the X-r ay sensitive CCD camera have shown that misfit dislocation features in the sample wafer topograph can be revealed in exposure times of less than 15 min. Results obtained from the CCD are presented. Finally, a n umber of further improvements to the camera system are possible using recent developments in CCD technology which will improve the resolutio n and sensitivity and allow higher resolution topographs to be obtaine d in around 30 s, close to the goal for real-time imaging of layer gro wth by molecular beam epitaxy (MBE). These further developments and th e implications on the performance of a new camera system for X-ray top ography are discussed.