Effects of low ion dose on SE imaging and orientation dependent Ga-ion channeling

Grain contrasts produced during ion induced secondary electron imaging depend upon grain orientation and ability of Ga-ion beam to channel in it. The current study aims to investigate critical Ga-ion dose for Ni-alloy where a transition from grain surface imaging to sputtering dominated Ga-ion channeling occurs. It is observed that critical dose is in the vicinity of 1015 ions/cm2. Strong orientation dependent Ga-ion channeling effects were observed at dose values higher than 1017 ions/cm2. When a normalized orientation dependent grain transparency factor was estimated for each grain in a limited sampling volume, it was observed that despite low sampling volume for a random polycrystalline orientations and variation in Ga-ion dose, the range of sputter depth variation during Ga-ion channeling remains above 80% indicating dose or sampling volume (for randomly oriented poly-crystals) independency in the sputter dominated dose region. This study attempts to establish a correlation between high resolution imaging, applied Ga-ion dose and orientation dependent Ga-ion beam channeling effects.