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Low-energy ion bombardment of a Au thin film by 0.5 keV Ar+ forms self-organized nanoclusters that display quantum size effects. The reduction of Au coverage with sputtering time is quantified with x-ray photoemission spectroscopy, and a decrease of both the rms roughness and correlation length is measured by STM. Neutralization of scattered 3 keV Na+ and K+ alkali-metal ions is used to probe the electronic states of the sputter-induced nanoclusters. The neutral fractions gradually increase as the cluster dimensions decrease, indicating that the electronic structure is similar to that of clusters grown by deposition.

Metal oxide semiconductor field effect transistor memories with Ge∕Si heteronanocrystals (HNCs) as floating gate were fabricated and characterized. Ge∕Si HNCs with density of 5×1011cm−2 were grown on n-type Si (100) substrate with thin tunnel oxide on the top. Enhanced device performances including longer retention time, faster programming speed, and higher charge storage capability are demonstrated compared with Si nanocrystal (NC) memories. The erasing speed and endurance performance of Ge∕Si HNC memories are similar to that of Si NC devices. The results suggest that Ge∕Si HNCs may be an alternative to make further floating gate memory scaling down possible.

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The neutralization of scattered low-energy alkali-metal ions is used to investigate the internal polarization of oxygen adatoms on a Ta surface. The neutral fraction of 3 keV Na scattered from Ta is 50% from the clean surface and 15% in the presence of oxygen, while the work function is unchanged. These observations can be reconciled if the adatoms were internally polarized, leading to multiple dipoles that each contribute to the work function.