Influence of melt convection on distribution of indium inclusions in liquid-encapsulated Czochralski-grown indium phosphide crystals

Abstract

Indium (In) inclusions have been found in 〈100〉 indium phosphide (InP) single crystals grown in In-rich melt by the liquid-encapsulated Czochralski (LEC) method. Two kinds of In inclusions with different morphologies, one is lath-like and the other is polyhedral, have been observed. Most of the In inclusions are lath-like and their long sides are always parallel to the $$[0\overline{1}1]$$ or $$[0{\overline{1}}{\overline{1}}]$$ orientation. In (100) InP wafers, these inclusions mainly distribute in two regions viz., center of the wafer and annular belt at a certain distance from the center. These special distributions of In inclusions in InP crystals were found in our experiments for the first time. In order to clarify the cause of the special distributions of In inclusions, numerical simulations have been carried out on the melt convection in the process of InP crystal growth. The results show that the rotations of crystal and crucible significantly affect the number and direction of convection cells in the melt, which have a great influence on the enrichment and distribution of excess In at the solid–liquid interface. Different melt convections modify the radial distributions of excess In atoms near the solid–liquid interface and result in different radial distributions of In inclusions in the crystals.