SILICON INCORPORATION IN LEC GROWTH OF SINGLE-CRYSTAL GALLIUM-ARSENIDE

Recent reports suggest that melt stoichiometry has a strong effect on silicon dopant incorporation in the LEC growth of GaAs single crystals. Our studies show that melt stoichiometry has no-effect on silicon incorporation. Using a low pressure LEC process in a high volume manufacturing environment we routinely grow 2 inch or 3 inch diameter, up to 4 kg, single crystals of Si-doped GaAs with dislocation densities as low as 100 cm-2. Crystals with Si concentrations ranging from 10(16) to 10(19) cm-3, grown from melts having Ga/As ratios ranging from 0.75 to 1.4 and contained in quartz crucibles, all have a compensation ratio of about 0.5. Contamination of the melt by Si from the quartz crucible as well as removal of Si from the melt by the B2O3 encapsulant must be considered when interpreting Si segregation data. In the course of the work with As-rich melts, the excess As in the melt gave rise to constitutional supercooling resulting in interface breakdown similar to that observed for excess dopants. This is the first time that this phenomena bas been reported for melt growth of GaAs single crystals.