SYNCHROTRON SECTION TOPOGRAPHIC STUDY OF DEFECTS IN InP SUBSTRATES AND QUATERNARY LASER STRUCTURES.

Indium phosphide single crystals grown by the liquid encapsulated Czochralski (LEC) and vertical gradient freeze (VGF) techniques are studied with x-ray diffraction topography using synchrotron radiation. Section topographs shows that while the VGF substrates are of a higher quality than the LEC ones, the defect level in epitaxial layers is more strongly determined by the quaternary layer composition and lattice match than by by threading dislocation from substrate.