Large capacitance-voltage hysteresis loops in SiO2 films containing Ge nanocrystals produced by ion implantation and annealing

C. J. Park, Kyoo Ho Cho, Weiling Yang, H. Y. Cho, Suk‐Ho Choi, R. G. Elliman, Joon-Young Han, Chungwoo Kim

Applied Physics Letters · 2006 · 66 citations · 16 references

Concepts

Abstract

Metal-oxide-semiconductor structures containing Ge nanocrystals (NCs) of 3–4nm diameter and 2×1012cm−2 density are shown to exhibit capacitance-voltage hysteresis of 20.9V, one of the largest observed in Ge-NC based nonvolatile memories. The Ge NCs were fabricated in an oxide of 30nm thickness by ion implantation with 30keV Ge2− ions to an equivalent fluence of 1×1016Gecm−2 followed by annealing at 950 °C for 10min. Secondary ion mass spectroscopy and transmission electron microscopy demonstrate the existence of Ge NCs whose average distance from the SiO2∕Si interface is about 6.7nm. It is shown that the memory effect is a likely consequence of charge trapping at Ge NCs and that it is enhanced by accurately controlling the distribution of Ge NCs with respect to the Si∕SiO2 interface.

References

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