Determination of 3-Dimensional Defect Structures in Gallium Arsenide Epilayers on Silicon Using White Beam Synchrotron Radiation Topography in both Transmission and Grazing Bragg-Laue Geometry.

Abstract

AbstractWhite beam synchrotron topography in both transmission and grazing Bragg-Laue geometries has been used to reveal the 3-dimensional defect structure in MBE grown GaAs epilayers on Si. Defects observed and characterized include substrate threading dislocations and interfacial dislocations. Dislocation line direction and Burgers vector analysis was performed on transmission topographs. The relationship between substrate threading dislocations and interfacial dislocations was established. In the grazing Bragg-Laue case, manipulation of geometry enabled depth profiling of defect structures in the epilayer. The position of the interfacial dislocations was verified by correlating penetration depth analysis with the visibility of the dislocations under different diffraction conditions.This technique affords a rapid and non-destructive way of quantitatively characterizing processing induced damage in such systems.