Si implantation in GaAs

Abstract

High-resolution Rutherford backscattering, transmission electron microscopy, and proton-induced x-ray emission with channeling have been used to investigate the damage and lattice site location of Si-implanted GaAs. Semi-insulating Cr-doped GaAs(100) crystals were implanted at room temperature with Si+ ions of single (120 keV) and multiple energies (50–400 keV). The total dose of implanted ions varies from 3×1015 cm−2 to 5×1015 cm−2. The residual damage and the lattice location of the implant are determined after 15 min annealing of the samples at 850 °C and 950 °C. It is shown that about 60%–70% of the Si atoms occupy substitutional lattice sites. The amount of precipitation has been evaluated and found to be very low (≤2%). For the dose of 5×1015 cm−2, microtwins lying on the (111) planes are found to be present after annealing at 850 °C in addition to the usual dislocation loops. However, after annealing at 950 °C, the primary residual damage consists of dislocation loops in addition to some small precipitates. Electrical activation efficiency has been measured in the case of 3×1015 cm−2 implant and found to be very low (≤2%). SiGa–SiAs neutral pair association is suggested to be the most probable reason for low electrical activity.