INFLUENCE OF BORON IN SEMIINSULATING GAAS CRYSTALS ON THEIR ELECTRICAL ACTIVATION BY SI-ION IMPLANTATION

The influence of boron on the activation of silicon ions implanted in semi-insulating GaAs crystals grown by liquid encapsulated Czochralski (LEC) method from As-rich melt was investigated using crystals with the same carbon concentration and the same deep donor (EL2) concentration. The resistivity of the crystal was not affected by the boron concentration. The sheet resistivity of the implanted layer, however, became higher with increase of the boron concentration. An analysis of the electrical properties of the implanted layer suggested that the occupation rate of the implanted silicon at As site (Si(As)), Which decides the acceptor level, increased with the boron concentration. The dependence of this occupation rate was influenced by the annealing temperature for activation in the region of low boron concentration under 15 X 10(16) cm-3.