SURFACE-TOPOLOGY OF GAAS(100) AFTER FOCUSED ION-BEAM IMPLANTATION OF SI++

GaAs(100) was implanted with Si++ doses ranging from 3 x 10(13) to 3 x 10(16) cm(-2) using a focused ion beam. The surface topology-and roug hness of implanted lines and squares was studied by atomic force micro scopy. Above a threshold dose, protrusions of the ion beam treated are as in the range of 1-15 nm in heights and an increase in surface rough ness were found. The height of the protrusions and surface roughness i ncrease with increasing implantation dose up to a saturation level. Bo th the onset of substrate bulging and saturation of the effect are bot h dependent on the linewidth of the implant. Different causes for the protrusions are discussed. From Monte Carlo simulations, it is deduced that the volume expansion is most likely due to the creation of vacan cies during implantation. (C) 1997 American Institute of Physics.