A MECHANISM FOR TWIN FORMATION DURING CZOCHRALSKI AND ENCAPSULATED VERTICAL BRIDGMAN GROWTH OF III-V COMPOUND SEMICONDUCTORS

Conditions are derived for which nucleation in twin orientation on an ''edge'' facet during the Czochralski growth of semiconductors is ther modynamically favoured over nucleation in the correct orientation. The model is based on ideas presented by Voronkov [Sov. Phys.-Cryst. 19 ( 1975) 573] concerning the conditions necessary for the edge facets to be anchored at the three phase boundary. It is shown that the conditio ns are satisfied for GaAs, InP and InSb but not for Ge and Si. The mai n features of twinning in the III-V compounds are accounted for and pr edicted conditions for the avoidance of twinning are listed.