Reversible charging effects in SiO2 films containing Si nanocrystals

Abstract

Reversible charging effects are observed in metal–insulator–semiconductor structures which have been ion implanted and annealed to produce Si nanocrystals in the insulating ${\mathrm{SiO}}_{\mathrm{2}}$ layer. The shifts in current–voltage $\mathrm{(I–V)}$ and capacitance–voltage $\mathrm{(C–V)}$ curves are induced by forward constant voltage stress or UV light exposure, and can be explained by hole charging of the nanocrystals in the insulator layer. A reverse constant voltage stress is shown to recover the original $\mathrm{I–V}$ curve and partially recover the original $\mathrm{C–V}$ curve. For a sample implanted with a Si dose of ${\text{3×10}}^{16} {\mathrm{Si cm}}^{\mathrm{-2}},$ the voltage shift of the $\mathrm{I–V}$ curve produced by a forward voltage stress of $\text{V=−10\hspace{0.05em}}\mathrm{V}$ for 5 s is 1.2 V, which is shown to be in reasonable agreement with simple estimates based on nanocrystal charging.