Carbon ion implantation in GaAs

Atom and carrier concentration profiles in carbon-ion-implanted GaAs have been measured. Ion implantation of carbon is performed at 300 keV with dose of 1.0 × 1014 ions/cm2. Carbon concentration profile obtained by secondary ion mass spectrometry measurement is in good agreement with the profile obtained by Monte Carlo simulation. The implanted carbon does not diffuse markedly with annealing at 900°C because the diffusion coefficient is below 4 × 10-16 cm2/s for the ion-implanted carbon. Therefore, a shallow carrier concentration profile is formed after annealing. Activation efficiency is 17% at the surface (depth less than 0.47 μm). However, this efficiency is as low as 4% in deeper regions. The lower activation efficiency in deeper regions in due to the suppression of activation by the precipitation of carbon after the annealing.