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%). Si_Ga–Si_As neutral pair association is suggested to be the most probable reason for low electrical activity.