RESIDUAL DISORDER IN LOW-PRESSURE, LOW THERMAL-GRADIENT LIQUID ENCAPSULATED CZOCHRALSKI GALLIUM-ARSENIDE OBSERVED IN HIGH-RESOLUTION SYNCHROTRON DIFFRACTION IMAGING

High resolution synchrotron X-radiation diffraction images of low ther mal gradient, low pressure, liquid encapsulated Czochralski (LEG) sili con-doped gallium arsenide display a degree of crystalline order that is far higher than that found in undoped conventional LEC material. No distinct Volume irregularity is observed in one crystal where it is u nstrained. Only a set of surface-treatment-related dislocations is pro minent in a second. A third crystal exhibits two distinct sets of quas i periodic dislocations, which have been analyzed in detail. The resul ts support a model previously proposed for the evolution of disorder i n gallium arsenide and suggest the role that silicon plays in its cont rol.