Energy dependence of nanopillars formation on InSb semiconductor surfaces under gallium FIB and noble gas ions beam irradiation

We have studied the formation and evolution of ion beam-induced pillars growth on InSb(0 0 1) surface through a comparison of irradiation with Ga (Focused Ion Beam) and noble gas ion (Ar, Kr, Xe) beams. Room temperature, normal incidence ion irradiation was carried out with the ion beam energy of 1-3 keV for noble gas and 3-30 keV for FIB Ga ions. The surface morphology of the developed structures and their chemical composition were investigated by means of scanning and transmission electron microscopy (SEM/TEM). We have examined the evolution from the initial flat InSb surface, through clusters formation, at initial stages of irradiation (ion beam fluence of 5 × 1016 ions/cm2), to the pillar structure formation at higher ion fluences (2.8 × 1017 ions/cm2), for both kinds of projectiles. The projectile ion energy dependence of the pillar size, height and density was studied for both kinds of ion species for the first time. It has been found that the pillar sizes and heights exhibit the power-law dependence on projectile energy with the same exponent for both kinds of the ion species. The TEM measurements uncovered crystalline InSb core of the pillar and In/Ga enriched amorphous tip and shell structure. We confirmed a universal mechanism of pillars formation based on redeposition of the sputtered sample material for both ion species i.e. noble gas ions and Ga FIB.