Epilayer and interface defects associated with relaxation of SiGe on Si studied by slow positron implantation

The first results of a positron study of relaxation in a SiGe/Si heterostructure system are presented. The Doppler-broadened annihilation lineshape parameter has been measured as a function of positron implantation energy, and a simple model for the annihilation depth profile has been used to fit the data. The results suggest that there is significant positron trapping at defect sites within the relaxed epilayer and at the mismatched interface.