Growth-twinning in zincblende crystals: further insights fromstudies of liquid encapsulated Czochralski (LEC) grown InP singlecrystals

摘要

Synchrotron white beam X-ray topography (SWBXT) combined withchemical etching and Nomarski optical microscopy have been employed toinvestigate the phenomenon of twinning in sulfur doped, LEC grown〈100〉 InP single crystals. Results confirm the generalprediction of Hurle that twins nucleate in regions where {111} edgefacets are anchored to the three phase boundary (TPB), and that twinningproduces a {111} external facet on the shoulder region of the crystal.However, some specific aspects of Hurle's theory were corrected by thisexperimental study. A detailed X-ray examination revealed the appearanceof a {115} external shoulder facet immediately before the occurrence oftwinning. The location at which the twin nucleates is the point wherethe {115} shoulder facet is converted to a {111} external shoulderfacet. This twinning mechanism allows for a reduction in free energy byconverting the facet from a {115} to a {111} plane