Dose‐rate effects in focused‐ion‐beam implantation of Si into GaAs

Ion current densities in focused‐ion‐beam (FIB) implantations are several orders of magnitude greater than those of conventional broad‐beam implantations. The corresponding increase in dose rate during implantation is shown to affect parameters of interest in device fabrication. FIB and broad‐beam Si implants into GaAs at energies from 70 to 280 keV and at doses from 3×1012 to 1014 cm−2 are characterized using secondary ion mass spectroscopy (SIMS) and Hall‐effect measurements. Reduced straggle, decreased activation, and modified carrier profiles are observed for FIB implants, particularly at higher energies and doses. These effects are attributed to dose‐rate‐dependent lattice damage.